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I. Add a scientific article how understanding various DNA technics helped us to investigate crime. Articles should not be repeated (every student will share a different one). II. Summarize 2 other articles and place your Google doc on BB.

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I. Add a scientific article how understanding various DNA technics helped us to investigate crime. Articles should not be repeated (every student will share a different one). II. Summarize 2 other articles and place your Google doc on BB.

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Forensics and DNA: how genetics can help solve crimes by Sarah Sharman

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Forensics and DNA: how genetics can help solve crimes by Sarah Sharman

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The article explains how DNA evidence can be collected from crime scenes, including blood, hair, and other biological materials. The piece emphasizes the advancements in DNA technology, such as DNA profiling and genetic databases, which improve the accuracy of investigations. It also touches on the ethical considerations surrounding genetic data and privacy concerns, while illustrating real-world examples of how DNA has been useful in liberating wrongfully convicted individuals. Overall, the article underscores the transformative impact of genetics on criminal justice.

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by: Sarah Sharman, PhD, Science writer
The true crime genre really boomed over the past few years. Hundreds of true crime podcasts and documentaries are available in our streaming feeds. And I will admit, as a 30 something year-old who grew up watching shows like CSI and Criminal Minds, I got caught up in the true crime wave.

Every week I listen to My Favorite Murder and The Murder Squad podcasts. I binged the documentary shows The Jinx and Making a Murderer. I even followed the breaking of the Golden State Killer case with bated breath. For me, though, I am most intrigued by the science behind the true crime curtain.

Forensic science, or the use of scientific methods to investigate crimes, has helped solve cases in the criminal justice system for centuries. Advances in DNA sequencing technology over the past few decades, however, has led to a surge in both convictions and exonerations for many crimes. Let's learn about how DNA and genetics play a role in solving cases.

DNA fingerprinting

There is DNA in nearly all of the cells of our body. It is made up of four nucleotide bases, represented by the letters A, T, C and G. Our cells use the DNA code to make the proteins and molecules necessary for all of the functions of our body. Because we each have a unique DNA code, it can also be used to identify individuals.

Forensic science increasingly relies on small bits of DNA left at crime scenes to link criminals to the crimes they commit. DNA can also be used to define paternity, exonerate the wrongly accused, and identify victims of crime, disasters, and war. Skin cells, blood, hair follicles, and saliva all contain DNA that can be used to identify an individual.

If you're a true crime fan like me, you have probably seen your fair share of investigations on popular television shows. Finding a perpetrator and bringing them to justice using DNA is often portrayed as a simple, exact, and infallible method. However, determining the likelihood of a DNA match between a suspect and a crime scene is a complicated process.

Although 99.9% of genomes are identical across all humans, there are regions of variation that are unique to each individual. A technique called DNA fingerprinting takes advantage of some of these differences to identify individuals based upon their DNA. Originating in the mid-1980s, DNA fingerprinting is now commonly used as a law enforcement tool.

DNA fingerprinting looks at differences in sections of DNA called short tandem repeats (STR). STRs consist of a string of repeating DNA nucleotides that are usually two to five bases long (like CAGCAGCAG or AATGAATGAATG for example). There are many STRs throughout the genome, each having different repeating units with different numbers of repeats.

Everyone has the same STR at the same place in the genome but the number of repeats varies between individuals. For example, I might have a CAG unit that is repeated five times while you have CAG repeating eight times. The differences in the number of repeats means that people have STRs of different lengths which can easily be measured using a few lab techniques.

To create a DNA fingerprint, DNA must first be extracted from a sample collected from a crime scene, a suspect, or an individual in a paternity case for example. The region containing each STR being analyzed is then copied many times using a technique called polymerase chain reaction. Afterwards, the STRs are separated according to their size. In the United States, law enforcement agencies and the Federal Bureau of Investigation (FBI) analyze 20 STRs when creating DNA fingerprints.

The profile from the sample from the crime scene is compared to the sample from the suspect (similar to the image to the right). If the STR profiles from the two samples do not match, the individual would be excluded as the source of the crime scene evidence (Suspects 1 and 2). But ​​if the two samples match across all 20 STRs (Suspect 3), a statistical calculation would be made to determine the frequency at which the full set of STRs is observed in the population. The likelihood of any two individuals having identical STR profiles is less than one in a quintillion (1,000,000,000,000,000,000).

DNA profiles can be entered into a database called Combined DNA Index System (CODIS) so that federal, state, and local agencies can exchange and compare DNA profiles electronically. When a suspect's identity is unknown, law enforcement can enter the crime scene DNA profile into CODIS to see if it matches any other profiles that have been uploaded. Comparing a profile to others in CODIS can link crimes together and link suspects to a crime scene.

Forensic genealogy

DNA fingerprinting does not always turn up a viable lead. For cases that cannot be solved using DNA fingerprinting, there are new and emerging technologies to help solve crimes. One emerging technique, called forensic genealogy, combines DNA analysis with traditional genealogy research to generate investigative leads in crimes. The most widely publicized case that has been solved using forensic genealogy is the Golden State Killer case.

Instead of looking at STRs like DNA fingerprinting, forensic genealogy examines more than half a million single nucleotide changes to DNA (called single nucleotide polymorphism, or SNP). Using the SNPs, scientists can identify sections of DNA that are shared between samples, like a crime scene sample and an individual.

The SNP profile that is created from a crime scene sample can be entered into a public DNA database (like GedMatch). The SNP profile is compared against the genetic profiles of individuals who voluntarily entered their DNA profile into the databases. Using the profiles, genetic genealogists piece together family trees in hopes of identifying individuals from their distant genetic relatives.

Once a potential suspect has been identified, law enforcement must fully investigate each suspect. If they think a suspect is a good match based on the rest of the information in the case, law enforcement must lawfully obtain a DNA sample from the suspect to compare to the crime scene DNA. Only if there is an exact DNA match can an arrest be made.

DNA is giving does their names back

HudsonAlpha Discovery™, a genetic sequencing lab located on the HudsonAlpha Institute for Biotechnology campus in Huntsville, Alabama, is doing their part to help John and Jane Does regain their identities. The company supports the work of the nonprofit organization DNA Doe Project in identifying unidentified victims from cold cases.

The DNA Doe Project uses forensic genealogy to identify John and Jane Does. On April 10, 2018, just two weeks before the Golden State Killer was arrested using the same technology, the DNA Doe Project announced that it had used genetic genealogy to identify a Jane Doe, previously known as the "Buckskin Girl" . Since that first case, the DNA Doe Project has helped identify more than 40 victims in cold cases using forensic genealogy.

HudsonAlpha Discovery plays a key role in these forensic genealogy cases- performing whole genome sequencing on the samples of DNA. They have worked on more than 1,100 forensic cases with the DNA Doe Project and other agencies. The most recent case for which HudsonAlpha Discovery provided sequencing services was the identification of a previously unidentified victim of the sexual predator and serial killer John Wayne Gacy.

DNA is a powerful tool for forensic science and companies like HudsonAlpha Discovery and the DNA Doe Project are helping to make it accessible for more victims and their families.

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Forensics and DNA: how genetics can help solve crimes

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by: Sarah Sharman, PhD, Science writer The true crime genre really boomed over the past few years. Hundreds of true crime podcasts and documentaries are available in our streaming feeds. And I will admit, as a 30 something year-old who grew up watching shows like CSI and Criminal Minds, I got caught up in the true crime wave.

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DNA is often used in solving crimes. But how does DNA profiling actually work?

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DNA is often used in solving crimes. But how does DNA profiling actually work?

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The article explains how investigators use DNA profiling, specifically through the analysis of short tandem repeats (STRs), to identify individuals from biological material at crime scenes. The process begins with collecting DNA samples (e.g., from a knife handle) and purifying it in a lab. DNA profiling focuses on STR regions, where certain sequences of bases are repeated. These repeats vary between individuals, creating a unique DNA profile. Investigators compare the DNA profile from the crime scene to reference profiles from suspects or databases. If a match is found, they can identify the person whose DNA was present. In cases of mixed DNA, software helps separate the profiles, though low quantities of DNA can complicate analysis. DNA profiling only identifies "whose biological material is present" but does not reveal how or when the material got there.

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DNA profiling is frequently in the news. Public interest is sparked when DNA is used to identify a suspect or human remains, or resolves a cold case that seems all but forgotten.

Very occasionally, it is in the media when the process doesn't work as it should.

So what is DNA profiling and how does it work - and why does it sometimes not work?

Read more: Australia has 2,000 missing persons and 500 unidentified human remains - a dedicated lab could find matches

A short history of DNA profiling

DNA profiling, as it has been known since 1994, has been used in the criminal justice system since the late 1980s, and was originally termed "DNA fingerprinting".

The DNA in every human is very similar - up to 99.9% identical, in fact. But strangely, about 98% of the DNA in our cells is not gene-related (i.e. has no known function).

This non-coding DNA is largely comprised of sequences of the four bases that make up the DNA in every cell.

But for reasons unknown, some sections of the sequence are repeated: an example is TCTATCTATCTATCTATCTA where the sequence TCTA is repeated five times. While the number of times this DNA sequence is repeated is constant within a person, it can vary between people. One person might have 5 repeats but another 6, or 7 or 8.

There are a large number of variants and all humans fall into one of them. The detection of these repeats is the bedrock of modern DNA profiling. A DNA profile is a list of numbers, based on the repeated sequences we all have.

The use of these short repeat sequences (the technical term is " short tandem repeat" or STR) started in 1994 when the UK Forensic Science Service identified four of these regions. The chance that two people taken at random in the population would share the same repeat numbers at these four regions was about 1 in 50,000.

Now, the number of known repeat sequences has expanded greatly, with the latest test looking at 24 STR regions. Using all of the known STR regions results in an infinitesimally small probability that any two random people have the same DNA profile. And herein lies the power of DNA profiling.

How is DNA profiling performed?

The repeat sequence will be the same in every cell within a person - thus, the DNA profile from a blood sample will be the same as from a plucked hair, inside a tooth, saliva, or skin. It also means a DNA profile will not in itself indicate from what type of tissue it originated.

Consider a knife alleged to be integral to an investigation. A question might be "who held the knife"? A swab (cotton or nylon) will be moistened and rubbed over the handle to collect any cells present.

The swab will then be placed in a tube containing a cocktail of chemicals that purifies the DNA from the rest of the cellular material - this is a highly automated process. The amount of DNA will then be quantified.

If there is sufficient DNA present, we can proceed to generate a DNA profile. The optimum amount of DNA needed to generate the profile is 500 picograms - this is really tiny and represents only 80 cells!

How foolproof is DNA profiling?

DNA profiling is highly sensitive, given it can work from only 80 cells. This is microscopic: the tiniest pinprick of blood holds thousands of blood cells.

Consider said knife - if it had been handled by two people, perhaps including a legitimate owner and a person of interest, yet only 80 cells are present, those 80 cells would not be from only one person but two. Hence there is now a less-than-optimal amount of DNA from either of the people, and the DNA profiling will be a mixture of the two.

Fortunately, there are several types of software to pull apart these mixed DNA profiles. However, the DNA profile might be incomplete (the term for this is "partial"); with less DNA data, there will be a reduced power to identify the person.

Worse still, there may be insufficient DNA to generate any meaningful DNA profile at all. If the sensitivity of the testing is pushed further, we might obtain a DNA profile from even a few cells. But this could implicate a person who may have held the knife innocently weeks prior to an alleged event; or be from someone who shook hands with another person who then held the knife.

This later event is called "indirect transfer" and is something to consider with such small amounts of DNA.

Read more: Criminals can't easily edit their DNA out of forensic databases

What can't DNA profiling do?

In forensics, using DNA means comparing a profile from a sample to a reference profile, such as taken from a witness, persons of interest, or criminal DNA databases.

By itself, a DNA profile is a set of numbers. The only thing we can figure out is whether the owner of the DNA has a Y-chromosome - that is, their biological sex is male.

A standard STR DNA profile does not indicate anything about the person's appearance, predisposition to any diseases, and very little about their ancestry.

Other types of DNA testing, such as ones used in genealogy, can be used to associate the DNA at a crime scene to potential genetic relatives of the person - but current standard STR DNA profiling will not link to anyone other that perhaps very close relatives - parents, offspring, or siblings.

DNA profiling has been, and will continue to be, an incredibly powerful forensic test to answer "whose biological material is this"? This is its tremendous strength. As to how and when that material got there, that's for different methods to sort out.

Read more: New technology lets police link DNA to appearance and ancestry - and it's coming to Australia

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DNA is often used in solving crimes. But how does DNA profiling actually work?

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DNA profiling is frequently in the news. Public interest is sparked when DNA is used to identify a suspect or human remains, or resolves a cold case that seems all but forgotten. Very occasionally, it is in the media when the process doesn't work as it should.

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How Louisiana police are using a DNA 'lab in a box' to solve crimes 

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How Louisiana police are using a DNA 'lab in a box' to solve crimes 

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When a pair of suspects fled a routine traffic stop and shot at a Baton Rouge-area police officer in 2020, DNA at the crime scene helped police quickly arrest one suspect. This is because Louisiana was the first state in the country to work with the FBI to integrate Rapid Dna programs into the booking process. Many describe it as a "lab in a box," because the machine analyzes samples against the combined DNA Index System (CODIS), a national database of DNA profiles. With the new machines, officers can get that information on-site in less than 90 minutes rather than sending it to a lab and taking weeks for the results to return. Phillip Simmers, a DNA analyst at Louisiana State police Crime Lab stated, "It's the same [forensic] technologies that crime teams have been using for decades. Rapid DNA just takes the technology and miniaturized it and makes it portable." This technology can aid in arrests and potentially keep criminals from being unknowingly released. The speediness can also help lessen the burden of backlogs at crime labs. As well as strengthens the law enforcement, help the communication, and keep the communities safe. In the last 8 months, the Louisiana state police report five people have been connected to previous crimes, via Rapid DNA, including a 2013 homicide, a 202 carjacking case that was being investigated by the Georgia Bureau of investigations , 2 burglaries, and the police officer shooting in the Baton Rouge area. The machines can help identify arrestees wanted in connection to sexual assault, murders, kidnappings, terrorism, and other major crimes while they are still in police custody. The technology can improve the process of DNA collection and identification of qualified arrestees, including those arrested on suspicion of a felony or about 20 different misdemeanors as identified by state law. There is some backlash due to privacy concerns. there are very few protections for Americans right now on DNA collection. Some can be implicated for crimes that they didn't commit purely based on a DNA sample. There are also risks of contamination and sample mix-up.

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How Louisiana police are using a DNA ‘lab in a box’ to solve crimes

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Louisiana is the first state in the country to work with the FBI to integrate Rapid DNA testing into the booking process. Law enforcement officials say the technology can aid arrests and help lessen the burden of backlogs.

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How Is DNA Profiling Used to Solve Crimes?

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How Is DNA Profiling Used to Solve Crimes?

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Although people may have the same eye color, hair color, skin color, etc... they do NOT have the same DNA.

What is DNA profiling and how does it help solve crimes?

The first step in DNA profiling consists of procuring relevant DNA samples. Only a small number of cells from a person’s skin or the root of a hair or from bodily fluids like blood, saliva, or semen is needed to build a unique DNA profile. Usually DNA samples are taken from crime scenes. If not, people can be asked to give up samples voluntarily. If there is enough info and evidence, someone may be ordered by law to provide DNA samples.

According to the article: "Once forensic scientists obtain a sample, they extract the DNA from cells in bodily fluids or tissues and copy it. They then separate the copied markers using a process known as capillary electrophoresis. This enables them to identify distinct markers and the number of repeats for different markers in each allele. The forensic scientists read this data using a chart called an electropherogram, which plots fragments of DNA and shows how many repeats there are for each marker and where they occur. Based on this chart, forensic scientists generate a DNA profiling definition that law enforcement professionals can read. This definition consists of a simple list of numbers, indicating how many repeat units are in each allele of 20 marker points throughout the person’s genome."

This article gives some examples of cases where this DNA profiling tool has been put into affect. It also talks about the history of DNA profiling as well as some pros and cons. I strongly recommend this article.

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DNA profiling is a state-of-the-art procedure that can be used to identify individuals on the basis of their unique genetic makeup. While people may share the same eye and hair color, and may even have similar facial features, they will not have the same DNA. This means the process can be useful in more accurately solving crimes. Forensic scientists can compare DNA found at a crime scene (from blood or hair, for example) to DNA samples taken from suspects. If there is no match, they may be able to rule out that suspect. If there is a match, police will likely want to take a closer look.

Such technology has revolutionized the criminal justice system over the past decades, increasing the likelihood of identifying criminals with virtual certainty. This can make it not only easier to identify perpetrators, but just as importantly decreases the odds of mistakenly putting innocent people behind bars.

In some cases, advances in DNA profiling have allowed law enforcement professionals to solve decades-old cases based on samples of DNA-rich material (such as fingernail clippings) collected before DNA testing was possible.

In other cases, a DNA profile may have been created at the time of the crime, but no match was found during the initial criminal investigation. This problem is now easier to overcome thanks to current database technology, which allows for DNA profiles to be stored and quickly searched. Alternately, DNA profiling advances have also enabled law enforcement to exonerate people who were wrongfully convicted of crimes they didn't commit.

The road to modern DNA profiling has been long, and it has taken forensic scientists decades of work and fine tuning to develop the highly accurate testing and analysis procedures available today. This article examines how current methods for DNA profiling came to be, and explains the procedure's current role in the contemporary criminal justice system, including its risks and benefits.

While DNA is one important factor in solving crimes, it is not the only one. Other aspects of criminal investigation - such as forensic psychology - remain an integral part of the process when it comes to capturing offenders. We'll also explore the role of forensic psychologists, their impact on criminal justice, and the profession's career outlook.

What Is DNA?

Before diving into the details of DNA profiling, it's important to understand what DNA is. Each person has unique DNA, an acronym that stands for deoxyribonucleic acid - the essential building block of the body's cells. DNA is made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). How these DNA bases are sequenced and organized in an organism's genome, a kind of genetic blueprint, provides cells with the information needed to build an organism.

Each cell in the body has a nucleus, an inner core, which holds chromosomes. DNA molecules make up these chromosomes. The chromosome contains "markers" - points that repeat short DNA sequences again and again. Just how many times a sequence repeats at each marker varies depending on the person. Every person has two copies - called alleles - of each marker: one from the mother's side and another from the father's. Forensic scientists can use so-called short tandem repeats (STRs) of DNA to identify individuals.

Because DNA is hereditary, DNA testing is often used in legal cases to determine maternity or paternity - for instance, when child custody and child support issues are at stake. As the U.K. National Health Service explains, scientists can compare the DNA of two persons using a blood test or even a saliva swab taken from the inside of the cheek. DNA testing can even be performed before a child is born, using tissue taken from the placenta or a sample of the amniotic fluid surrounding the child in the womb. This type of test can also be used to check for genetic abnormalities indicative of illnesses and diseases.

DNA is not just a unique personal identifier, but it can also reveal details about a person's heritage. Advances in DNA technology have allowed for the surge of at-home genealogy kits that provide people with information about their possible genetic background. Companies like 23andMe and Ancestry.com sell do-it-yourself DNA kits, which are delivered to the consumer's front door. The person provides a saliva sample and sends it back to the company, which analyzes the individual's ancestry.

For instance, a consumer DNA kit might identify a person's DNA shares key components with traditionally West African DNA, as the Live Science article "How Do DNA Ancestry Tests Really Work?" explains. The rise of DNA-driven genealogy databases is also one trend that has supported the increased use of DNA profiling in the criminal justice system.

What Is DNA Profiling?

The first step in DNA profiling is to procure relevant DNA samples. Only a small number of cells from a person's skin or the root of a hair - or from bodily fluids like blood, saliva, or semen - is needed to build a unique DNA profile. DNA is often discovered at crime scenes during police investigations, after which persons of interest may be asked to voluntarily provide their DNA sample. If there is a strong body of evidence against a suspect, the courts can order them to provide a DNA sample.

Once forensic scientists obtain a sample, they extract the DNA from cells in bodily fluids or tissues and copy it. They then separate the copied markers using a process known as capillary electrophoresis. This enables them to identify distinct markers and the number of repeats for different markers in each allele. The forensic scientists read this data using a chart called an electropherogram, which plots fragments of DNA and shows how many repeats there are for each marker and where they occur. Based on this chart, forensic scientists generate a DNA profiling definition that law enforcement professionals can read. This definition consists of a simple list of numbers, indicating how many repeat units are in each allele of 20 marker points throughout the person's genome.

Examples of Types of DNA Profiling Cases

The first recognized case of DNA profiling in the forensic science community was that of Colin Pitchfork. In 1986, a girl named Dawn Ashworth was sexually assaulted and murdered in Leicester, England. A man named Richard Buckland confessed to the crime, but police were not confident that he was the killer. They approached Alec Jeffreys, a genetics professor at the University of Leicester, for help. Jeffreys had previously discovered that each person's DNA exhibited distinct patterns that could be used to distinguish one person's DNA from another's. Jeffreys compared DNA from the crime to Buckland's, and as police had suspected, it did not match.

Jeffreys went on to analyze over 4,000 DNA samples voluntarily provided by men in the Leicester area who wanted to clear their names and help find the perpetrator. Still, no match was found. Then one man confessed that he had been paid to provide a false sample on behalf of the actual perpetrator - a man named Colin Pitchfork. When Pitchfork's DNA was checked, it matched the DNA at the crime scene. He was sentenced to life in prison in January of 1988.

DNA profiling can also be used to exonerate the wrongfully convicted. For instance, 70-year-old Craig Coley was freed from a California prison in 2017 after DNA testing cleared him of a double-murder he had been convicted of 1978.

Coley had been sentenced to life in prison without parole. Throughout his trial and afterward, he had always maintained his innocence. When biological samples from the crime scene were retested in 2015, the results showed the DNA at the crime scene did not match Coley's - and that other people's DNA was present. According to area police, the technology for testing the crime scene DNA sample wasn't available in the 1970s when Coley was convicted. Reuters reports that Coley is one of more than 350 people exonerated in the U.S since 1989 thanks to DNA testing.

The History of DNA Profiling

It has taken forensic scientists years to develop the highly accurate testing procedures that make examples like those above possible. Today's processes rely on the aforementioned STRs, short tandem repeats. A single STR used in today's forensics is some three to five DNA bases in length. In the past, much longer repeat segments of bases were required, measuring from hundreds to even tens of thousands. Also in the past, when DNA was isolated and separated into fragments, it was labeled using radioactive phosphorus and then examined using X-ray-sensitive film. The entire process took anywhere from six to eight weeks.

Today, the process is more streamlined thanks to the switch to STRs. Another advance that has made DNA profiling more efficient is the transition from gel electrophoresis to capillary electrophoresis to separate DNA. Gel electrophoresis can't withstand electric fields of more than 40V, while capillary electrophoresis can apply voltages of up to 30,000V, reducing separation time to mere minutes instead of hours.

Additionally, DNA analysis has advanced greatly due to the development of a technique known as polymerase chain reaction, or PCR. This process involves heating and cooling DNA samples in cycles, ultimately "amplifying" the DNA and making fragments easier to detect. With this development (which was ultimately recognized with a Nobel Prize, a landmark moment in DNA profiling history) forensic scientists are able to work with smaller amounts of biological evidence.

Previously, a bloodstain for example, would have to be at least the size of a dime or quarter to elicit enough DNA for a profile. With PCR, profiling is possible with even smaller amounts of blood. Today's DNA profiling is more sensitive. As a result, investigators can often retrieve DNA from minute numbers of skin cells left behind by a criminal. They can even distinguish the DNA of multiple individuals (for instance, if many people touched the same surface).

The DNA Profiling Process Today

Such advances in the technologies and processes used to collect and analyze DNA are just part of what makes advanced DNA profiling so useful. Another aspect is the rise of database technology. When law enforcement professionals can comb through large volumes of DNA data stored in computer databases, they have better odds of finding matches for material collected at crime scenes.

The Federal Bureau of Investigation (FBI), for example, relies on the Combined DNA Index System, or CODIS, which uses computer and DNA technologies to compare DNA profiles. It can generate investigative leads in scenarios where biological evidence, such as semen or blood, has been recovered from a crime scene. Each CODIS profile has a specimen identifier, the processing lab's identifier, and the actual DNA profile. Law enforcement in different jurisdictions can use CODIS to coordinate distinct investigations and share leads. Matches generated via CODIS allow law enforcement to pinpoint a suspect's identity.

In recent years, the criminal justice system has also turned to other types of databases - genealogy databases - to identify suspects. As mentioned before, private companies sell at-home DNA testing kits, which people can use to discover more about their genetic history. These companies often encourage users to upload their data for genealogical purposes. This enables them to more readily identify connections, even putting them in touch with distant relations.

In Spain, a woman who was taken from her biological parents as a baby under the Franco dictatorship found her biological family through such a DNA database. In some cases, police can also comb through these files for DNA profiling purposes, searching for individuals who may be criminal suspects or related to suspects.

In 2019, for instance, a 35-year-old cold case murder in Wisconsin was solved using DNA and genealogy databases. Following the 1984 rape and murder of a woman in Milwaukee, police were able to compose a DNA profile of the perpetrator based on semen found at the crime scene. There was no known suspect at the time, however, so police were unable to find a match for the sample. Decades later, police began searching through genealogy databases, which hold millions of DNA profiles, thinking they might find someone who was related to the perpetrator. They identified one individual who turned out to be the killer's second cousin. Through this family connection, they were able to trace the family tree and find the killer, whose DNA was a match with the sample collected from the crime scene over 30 years prior.

DNA Profiling Uses in the Criminal Justice System

These examples highlight some of the primary uses of DNA profiling in today's legal system. The process can be used to identify potential suspects and link suspects to a crime, proving they were at a certain place. DNA profiling also enhances the criminal system's accuracy. Eyewitness accounts are unreliable, particularly in high-pressure situations during the commission of a crime. In the article " The Neuroscience of Memory: Implications for the Courtroom," researchers note that memory distortions can cast doubt on eyewitness testimony. By comparison, DNA is scientifically accurate and thus more difficult to dispute.

It's clear that advances in DNA collection and analysis, combined with the power of DNA technology, have in many ways transformed the criminal justice system. However, it's important to note that although DNA profiling is highly accurate and can play a big role in catching criminals, it's only one part of the overall criminal justice process.

It takes more than DNA to convict a person of a crime. Forensic psychology remains an integral part of the process, for example. This application of psychology in the legal field is central to deepening law enforcement's understanding of criminal behavior. Forensic psychologists can help answer questions such as who committed a crime and why. It can also help discern why a person committed a crime in a certain manner - for instance, by opting for a particular weapon. Forensic psychologists also deal with the impact of crimes on victims and may work in victim advocacy.

DNA Profiling Pros and Cons

Although DNA profiling undoubtedly has many practical uses, there are some drawbacks. Questions have already been raised about the ethical implications of catching criminals based on searches of their family's DNA (as exemplified in the Wisconsin case noted earlier). Nature, the weekly scientific magazine, highlights a number of such instances and the fact that most people who use genealogy databases are unaware that law enforcement may be able to subpoena their information.

There are also ethical and privacy concerns when it comes to law enforcement storing DNA data from convicted criminals. Storing an individual's DNA, even if they have been convicted of a crime, can be seen as a violation of a basic human right to privacy.

The MIT Technology Review even goes so far as to call large-scale databases like those used to find the Golden State Killer a "national security leak waiting to happen." Unlike a credit card, which can be replaced, a person's genome can't be. The article argues that foreign intelligence could grab millions of American DNA profiles from a database and potentially use the information to identify the true identities of American diplomats or spies and their relatives. They could also pinpoint political information that could potentially be compromising. While this has yet to happen as far as we know, the possibility is very real. The technology is there, and so is the data.

Another concern with DNA profiling is the procedure itself. Although very accurate, it is not 100% foolproof. A partial DNA profile (one that is not complete), for example, may match with multiple people and should not serve as conclusive evidence.

DNA can also be abused, misused, or misunderstood, causing miscarriages of justice. In 2011, a careless lab error resulted in an innocent man being charged with rape because his DNA was erroneously found to match a sperm sample taken from the victim. It later became clear that the lab had mixed up its files. In short, DNA is just one piece of the criminal justice puzzle, and should not be relied on to the exclusion of other investigative and analytical tools.

Criminal Justice Beyond DNA - The Value of a Degree in Forensic Psychology

The cutting-edge science of DNA profiling requires professionals to work in laboratory settings that are removed from evidence collection and apart from the human element of criminal justice. While their work is an integral part of the modern criminal justice system, many who are interested in justice-related careers may be drawn to other specialties.

Consider forensic psychology, which provides the opportunity to examine crime as it relates to the human psyche in the cases of both perpetrators and victims. Those in the field may work to pinpoint future indicators of violent behavior, for example, or help victims through advocacy support. As a career, psychology as a whole is a growing field, with the U.S. Bureau of Labor Statistics (BLS) predicting a growth rate of 14% between 2018 and 2028.

Individuals who are interested in learning more about forensic psychology would do well to explore Maryville University's online BA in Forensic Psychology. The program covers both psychology core curricula, from social psychology to cognition, as well as criminal justice coursework covering everything from juvenile delinquency to multicultural issues. Students are further encouraged to gain practical experience through an internship, enabling them to understand the connection between course material and its real-world application.

This Maryville University online BA offers a comprehensive mixture of both theoretical and practical teaching. This approach is designed to prepare students for rewarding careers in a number of roles - in police departments or medical laboratories, working with parolees and probation offices, excelling as victim advocates, and beyond. The curriculum also provides a strong foundation for those interested in pursuing further education to become forensic psychologists.
If you're drawn to a career in criminal justice that performs beyond the lab - and takes into account the human condition - explore Maryville University's online BA in Forensic Psychology program today.
Recommended Reading BA Forensic Psychology Careers How to Become a Forensic Psychologist An Introduction to the World of Forensic Psychology Sources Chemical and Engineering News, "Thirty Years of DNA Forensics: How DNA Has Revolutionized Criminal Investigations" The Guardian, "DNA Database Helps one of Spain's 'Stolen Babies' Find Family" Investigative Genetics, "DNA Fingerprinting in Forensics: Past, Present, Future" JSTOR Daily, "How Forensic DNA Evidence Can Lead to Wrongful Convictions" Live Science, "How Do DNA Ancestry Tests Really Work?" The Malaysian Journal of Medical Sciences, "Forensic DNA Profiling and Database" MIT Technology Review, "The DNA Database Used to Find the Golden State Killer Is a National Security Leak Waiting to Happen" National Review of Neuroscience, "The Neuroscience of Memory: Implications for the Courtroom" Nature, "The Ethics of Catching Criminals Using Their Family's DNA" NBC News, "35-Year-Old Cold Case Murder in Wisconsin Solved Using DNA and Genealogy" Reuters, "After DNA Test, California Man Freed From Prison in 1978 Double-Murder" The U.S. Bureau of Labor Statistics Occupational Outlook Handbook, "Psychologists" U.K. National Health Service, "What Is a Prenatal Paternity Test?" U.S. National Library of Medicine, What Is a Chromosome?" U.S. National Library of Medicine, "What Is DNA?"

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DNA Profiling: How Is It Used in Criminal Justice?

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DNA profiling is a state-of-the-art procedure that can be used to identify individuals on the basis of their unique genetic makeup. While people may share the same eye and hair color, and may even have similar facial features, they will not have the same DNA.

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DNA Mixtures: A Forensic Science Explainer

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DNA Mixtures: A Forensic Science Explainer

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What are DNA mixtures? And why are they sometimes so difficult to interpret?

Ryan Press explains how DNA profiling is a powerful tool for solving crimes, especially when the DNA evidence involves just one or two individuals. However, with advancements in technology, forensic scientists can now analyze DNA mixtures and trace amounts of DNA, like “touch DNA" ,(skin cells) making interpretation more complex. These new methods allow investigators to handle more sensitive evidence but also introduce uncertainties with these results. As DNA mixtures become more common, understanding these uncertainties is crucial for accurate interpretations in investigations and courtrooms.

The new methods in DNA analysis include advancements in DNA mixture analysis, which helps separate and interpret overlapping profiles from multiple samples at a crime scene. Forensic scientist now use “touch DNA” to detect even small amounts of DNA left behind from simple contact, making it easier to gather evidence from everyday surfaces. (people leaving behind skin cells when touching something) However, this also increases the chances of irrelevant DNA being detected. To manage these mixtures, forensic scientists rely on probabilistic genotyping software (PGS), which uses statistical models to estimate how likely it is that a suspect’s DNA contributed to the evidence. Also, high-sensitivity DNA method, like PCR, amplify small or degraded DNA samples, which help investigators to analyze even the smallest amounts of genetic material. These advancements offer powerful tools for crime scenes but also require careful analysis due to their problems.

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National Institute of Standards and Technology

# data[].attributes.attachment_link.title
DNA Mixtures: A Forensic Science Explainer

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What are DNA mixtures? And why are they sometimes so difficult to interpret?

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DNA Profiling in Forensic Science: A Review

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DNA Profiling in Forensic Science: A Review

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The article provides an overview of DNA profiling's significance in forensic investigations, detailing its historical development, methodologies, and applications, especially examining how scientists extract DNA from hard human tissue. It highlights DNA's uniqueness to individuals (except identical twins) and its critical role in identifying victims and suspects. The review traces the evolution of forensic genetics from early blood group identification to key advancements like Alec Jeffreys' DNA fingerprinting and Kary Mullis' PCR technique. The article explains DNA's structure and the human genome's composition, emphasizing the ideal properties for forensic DNA loci, such as high polymorphism and low mutation rates. It discusses various biological materials for DNA extraction, including blood and saliva, and outlines extraction methods like Chelex-100 and silica-based techniques. The basic steps of DNA analysis—extraction, quantification, amplification, and detection—are also described.

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As a library, NLM provides access to scientific literature. Inclusion in an NLM database does not imply endorsement of, or agreement with, the contents by NLM or the National Institutes of Health. Learn more about our disclaimer.

Glob Med Genet. 2021 Dec; 8(4): 135-143.

Abstract

DNA is present in most of the cells in our body, which is unique in each and every individual, and we leave a trail of it everywhere we go. This has become an advantage for forensic investigators who use DNA to draw conclusion in identification of victim and accused in crime scenes. This review described the use of genetic markers in forensic investigation and their limitations.

Keywords: deoxyribonucleic acid, polymerase chain reaction, base pairs, single-nucleotide polymorphism, simple sequence repeat

Introduction

Forensic identification is a universal method used to establish the veracity in the process of forensic investigation. Both criminalities and medico-legal identification are integrative parts of forensic identification, having probative value. The value of an identification method resides in the specialist's ability to compare traces left at the crime scene with traces found on other materials such as reference evidence. Through this procedure, one can compare traces of blood, saliva, or any biological sample left at the crime scene with those found on a suspect's clothes and with samples from the victim. Medico-legal identification is based on scientific methods or intrinsic scientific methods absorbed from other sciences, usually bio-medical sciences. Scientific progress in the last 30 to 40 years has highlighted and continues to highlight the role of the specialists in identification. Their role proves its significance in cases that have to do with civil, family, and criminal law, as well as in cases of catastrophes with numerous victims (accidents, natural disasters, terrorist attacks, and wars). Together with the discovery by Mullis in 1983 of the polymerase chain reaction (PCR), Sir Alec Jeffreys in the field of forensic genetics used this technique by studying a set of DNA fragments that proved to have unique characteristics, which were nonrecurring and intrinsic for each individual, the only exception being identical twins. Alec Jeffreys named these reaction products "genetic fingerprints." 1 PCR procedure is correct as per the reference.

Brief History of Forensic Genetics

In 1900, Karl Landsteiner distinguished the main blood groups and observed that individuals could be placed into different groups based on their blood type. This was the first step in development of forensic hemogenetics. 2

1915: Leone Lattes describes the use of ABO genotyping to resolve paternity case. 2

1931: Absorption-inhibition of ABO genotyping technique had been developed. Following on from this, various blood group markers and soluble blood serum protein markers were characterized. 2

In the 1960s and 1970s: Developments in molecular biology, restriction of enzymes, Southern blotting, 3 and Sanger sequencing 4 enabled researchers to examine sequences of DNA.

1978: Detection of DNA polymorphisms using Southern blotting. 5

1980: First polymorphic locus was reported. 6

1983: A critical development in the history of forensic genetics came with the advent of PCR process that can amplify specific regions of DNA, which was conceptualized by Kary Mullis, a chemist; later he was awarded Nobel Prize in 1993. 7

1984: Alec Jeffrey introduced DNA fingerprinting in the field of forensic genetics, and proved that some regions in the DNA have repetitive sequences, which vary among individuals. Due to this discovery, first forensic case was solved using DNA analysis. 8

DNA Structure and Genome

DNA was first described by Watson and Crick in 1953, as double-stranded molecule that adopts a helical arrangement. Each individual's genome contains a large amount of DNA that is a potential target for DNA profiling.

DNA Structure

DNA is often described as the "blue print of life," because it contains all the information that an organism requires in function and reproduction. The model of the double-helix structure of DNA was proposed by Watson and Crick. The DNA molecule is a polymer of nucleotides. Each nucleotide is composed of a nitrogenous base, a five-carbon sugar (deoxyribose), and a phosphate group. There are four nitrogenous bases in DNA, two purines (adenine and guanine) and two pyrimidines (cytosine and thymine). Each base is attracted to its complimentary base: adenine base always pairs with thymine base whereas cytosine base always pairs with guanine base ( Fig. 1 ). 9

Organization of DNA into Chromosomes

There are two complete copies of the genome in each nucleated human cell. Humans contain ∼3,200,000,000 base pairs (BPs) of information, organized in 23 pairs of chromosomes. There are 2 sets of chromosomes; 1 version of each chromosome is inherited from each parent with total of 46 chromosomes. 10 11 12

Classification of Human Genome 2

Based on the structure and function, Classification of Human Genome into following different types ( Fig. 2 ).

1. Coding and regulatory regions: The regions of DNA that encode and regulate protein synthesis are called genes. Approximately, a human genome contains 20,000 to 25,000 genes; 1.5% of the genome is involved in encoding for proteins.

2. Noncoding: Overall, 23.5% of the genome is classified under genetic sequence but does not involve in enclosing for proteins; they are mainly involved with the regulation of genes including enhancers, promoters, repressors, and polyadenylation signals.

3. Extragenic DNA: Approximately 75% of the genome is extragenic, of which 50% is composed of repetitive DNA and 45% of interspersed repeats. Four common types of interspersed repetitive elements are: (i) short interspersed elements, (ii) long interspersed elements, (iii) long terminal repeats, and (iv) DNA transposons. Tandem repeats consist of three different types: (i) satellite DNA, (ii) minisatellite DNA, and (iii) microsatellite DNA.

Genome and Forensic Genetics

DNA loci that are to be used for forensic genetics should have the following ideal properties:

Should be highly polymorphic.

Should be easy and cheap to characterize.

Should be simple to interpret and easy to compare between laboratories.

Should have a low mutation rate.

With recent advances in molecular biology techniques, it is possible to analyze any region with 3.2 billion BPs that make up the genome. 2

Biological Material

Three most important steps are collection, characterization, and storage.

Sources of Biological Evidence

Human body is composed of trillions of cells and most of them are nucleated cells, except for the red blood cells. Each nucleated cell contains two copies of individual's genome and can be used to generate a DNA profile. Usually, samples show some level of degradation but when the level of degradation is high, more cellular material is needed to produce a DNA profile. 13

Biological samples with nucleated cells are essential for forensic genetic profiling, such as: 14

Liquid blood or dry deposits.

Liquid saliva, semen, or dry deposits.

Hard tissues like bone and teeth.

Collection and Handling of Material at the Crime Scenes

Whole blood is considered as one of the widely used source of DNA. It is preserved in an anticoagulant (ethylenediamine tetra acetic acid) and conserved at 4°C for 5 to 7 days initially. After this period, DNA samples are kept at -20°C for few weeks or at -80°C for longer periods of time. Epithelial cells collected from crime scenes are harvested with sterile brush or bud. After harvesting, they are wrapped in plastic envelope or paper envelope and kept in a dry environment at room temperature. 15 It is essential that proper care is taken, such as maintaining integrity of the crime scene, wearing face masks and full protective suits during the investigation of scene, 16 17 18 as inappropriate handling of the evidence can lead to serious consequences. In worst cases, cross-contamination leads to high level of sample degradation; this can confuse or avert the final result of evidence.

Characterization of DNA Analysis: Basic Steps 1

Analysis of DNA involves four basic steps, which are as follows ( Fig. 3 ):

Detection of the DNA-amplified products.

DNA Extraction

The first DNA extraction was performed by Friedrich Miescher in 1869. Since then, scientists have made progress in designing various extraction methods that are easier, cost-effective, reliable, faster to perform, and producing a higher yield. With the advent of gene-editing and personalized medicine, there has been an increase in the demand for reliable and efficient DNA isolation methods that can yield adequate quantities of high-quality DNA with minimal impurities.

There are various methods of extraction as mentioned below, though commonly used are Chelex-100 method, silica-based DNA extraction, and phenol-chloroform method.

1. Chromatography-based DNA extraction method.

2. Ethidium bromide-cesium chloride (EtBr-CsCl) gradient centrifugation method.

3. Alkaline extraction method.

4. Cetyltrimethylammonium bromide (CTAB) extraction method.

5. Phenol-chloroform method.

6. Sodium dodecyl sulfate (SDS)-proteinase K method.

7. Silica column-based DNA extraction method.

8. Cellulose-based paper method.

9. Chelex-100 extraction method.

10. Filter paper-based DNA extraction method.

Chromatography-Based DNA Extraction Method

Chromatography-based DNA extraction method is used to isolate DNA from any kind of biological material. 19 This method is divided into three different types:

1. Size-inclusion chromatography: In this method, molecules are separated according to their molecular sizes and shape.

2. Ion-exchange chromatography (IEC): In this method, solution containing DNA anion-exchange resin selectively binds to DNA with its positively charged diethylaminoethyl cellulose group. 20 This method is simple to perform when compared with other DNA extraction methods. 19

3. Affinity chromatography: Protocol is similar to IEC; however it uses oligo that forms specific interaction with nucleic acid resulting in separation from the cell lysate. 19

This procedure is used for isolation of messenger ribonucleic acid (m-RNA).

It yields a very good quality of nucleic acids. 21

EtBr-CsCl Gradient Centrifugation Method

In 1957, Meselson et al developed this method. 22 DNA is mixed with CsCl solution, which is then ultra-centrifuged at high speed (10,000-12,000 rpm) for 10 hours, resulting in separation of DNA from remaining substances based on its density. EtBr is incorporated more into nonsupercoiled DNA than supercoiled DNA molecules resulting in accumulation of supercoiled DNA at lower density, and location of DNA is visualized under ultraviolet (UV) light.

Advantage:

This method is used to extract DNA from bacteria.

Limitations:

Greater amount of material source is needed.

Costly procedure due to long duration of high-speed ultra-centrifugation.

Alkaline Extraction Method

First introduced by Birnboim and Doly in 1979, this method is used to extract plasmid DNA from cells. 24 Sample is suspended in NaOH solution and SDS detergent for lysis of cell membrane and protein denaturation. Potassium acetate is then added to neutralize the alkaline solution, which results in formation of precipitate. Plasmid DNA in the supernatant is recovered after centrifugation.

Limitation:

Contamination of plasmid DNA with fragmented chromosomal DNA. 25

Silica Matrices Method

The affinity between DNA and silicates was described by Vogelstein and Gillespie in 1979. 26

Principle: Selective binding of negatively charged DNA with silica surface is covered with positively charged ions. DNA tightly binds to silica matrix, and other cellular contaminants can be washed using distilled water or Tris-EDTA. 27

Advantages:

Simple.

Limitation:

Silica matrices cannot be reused.

Salting-Out Method

Introduced by Miller et al 55 in 1988, this method is a nontoxic DNA extraction method.

Procedure: Sample is added to 3 mL of lysis buffer, SDS, and proteinase K, and incubated at 55 to 65°C overnight. Next, 6 mL of saturated NaCl is added and centrifuged at 2,500 rpm for 15 minutes. DNA containing supernatant is transferred into fresh tube and precipitated using ethanol. 28

Advantages:

This method is used to extract DNA from blood, tissue homogenate, or suspension culture.

High-quality DNA is obtained.

Reagents are nontoxic.28,29

Cetyltrimethylammonium Bromide (CTAB) Extraction Method

This method was introduced by Doyle et al in 1990. 30

Samples are added to 2% CTAB at alkaline pH. In a solution of low ionic strength, buffer precipitates DNA and acidic polysaccharides from remaining cellular components. Solutions with high salt concentrations are then added to remove DNA from acidic polysaccharides; later, DNA is purified using organic solvents, alcohols, phenols, and chloroform. 20

Limitations:

Toxic reagents like phenol and chloroform are used.

Phenol-Chloroform Method

This method was introduced by Barker et al in 1998. 31 Lysis containing SDS is added to cells to dissolve the cell membrane and nuclear envelope; phenol-chloroform-isoamyl alcohol reagent is added in the ratio 25:24:1. 28 Both SDS and phenol cause protein denaturation, while isoamyl alcohol prevents emulsification and hence facilitates DNA precipitation. The contents are then mixed to form biphasic emulsion that is later subjected to vortexing. This emulsion separates into two phases upon centrifugation, upper aqueous phase, composed of DNA, and the lower organic phase, composed of proteins. Upper aqueous phase is transferred to fresh tube and the lower organic phase is discarded. These steps are further repeated until the interface between the organic and aqueous phase is free from protein. 31 Later, sodium acetate solution and ethanol are added in 2:1 or 1:1 ratio, followed by centrifugation for separation of DNA from the solution. The pellet is washed with 70% ethanol to remove excess salt from the DNA and subjected to centrifugation for removal of ethanol. The pellet is dried and suspended in an aqueous buffer or sterile distilled water.

Advantages:

Used to extract DNA from blood, tissue homogenate, and suspension culture.

Inexpensive.

Limitation:

Toxic nature of phenol and chloroform. 28

SDS-Proteinase K Method

It was first introduced by Ebeling et al in 1974. 32 For extraction of DNA, 20 to 50 µL of 10 to 20 mg/mL proteinase K is added. SDS is added to dissolve the cell membrane, nuclear envelope, and also to denature proteins. The solution is incubated for 1 to 18 hours at 50 to 60°C and then DNA can be extracted using the salting-out method or phenol-chloroform method. 33

Silica Column-Based DNA Extraction Method

In this method, 1% SDS, lysis buffer (3 mL of 0.2 M tris and 0.05 M EDTA), and 100 mg of proteinase K are added to sample and incubated at 60°C for 1 hour, and this mixture is added in a tube containing silica gel. To this, phenol-chloroform is added in the ratio of 1:1 and centrifuged for 5 minutes. This separates the organic phase containing proteins beneath the silica column while aqueous phase containing DNA above the gel polymerase, and then aqueous layer is transferred to the tube and dissolved in TE buffer.

Advantages:

Increase in purity of extracted DNA.

Silica gel prevents physical contact with toxic reagents.

DNA yield is 40% higher than organic solvent-based DNA extraction method.34

Magnetic Beads Method

Trevor Hawkins filed a patent "DNA purification and isolation using magnetic particles" in 1998. 35

Magnetic nanoparticles are coated with DNA-binding antibody or polymer that has specific affinity to bind to its surface. 36 In this method, a magnetic field is created at the bottom of the tube using an external magnet that causes separation of DNA-bound magnetic beads from cell lysate. The supernatant formed is rinsed, and beads aggregated at the bottom can be eluted with ethanol precipitation method; and the magnetic pellet is incubated at 65°C to elute the magnetic particles from the DNA. 28

Advantages:

Time taken is less than 15 minutes.

Faster compared with other conventional methods.

Little equipment is required.

Cellulose-Based Paper

It was first introduced by Whatman in 2000, who filed a patent titled "FTA-coated media for use as a molecular diagnostic tool." Cellulose is a hydroxylated polymer with high binding affinity for DNA. Whatman FTA cards are commercially available as cellulose-based paper that is widely used for extraction of DNA. 38 They are impregnated with detergents, buffers, and chelating agents that facilitate DNA extraction. About 1 to 2 mm of sample area is removed with micro punch and further processed for downstream applications. 19 39

Advantages:

Extraction of DNA using cellulose-based paper is fast.

Does not require laboratory expertise.

Easy storage of sample.40

Chelex-100 Extraction Method

In 2011, Xlonghui et al 40 patented a DNA extraction method using Chelex-100. Chelex resin is used to chelate metal ions acting as cofactors for DNases. After incubating overnight, 5% Chelex solution and proteinase K are used to degrade the added DNases, which are later boiled in 5% Chelex solution to lyse the remaining cell membranes, and to denature both proteins and DNA. Also, 5% Chelex solution prevents DNA from being digested by DNases that remain after boiling, hence stabilizing the preparation. The resulting DNA can then be concentrated from the supernatant after centrifugation.

Advantages:

Reduced risk of contamination.

Use of single test tube.

Limitation:

Isolated DNA can be unstable. 38

Filter Paper-Based DNA Extraction Method

This method was described by Ruishi and Dilippanthe in 2017. DNA extraction method using filter paper can be used to isolate DNA from plant sources. A spin plate composed of 96-well plate is used, with a hole 1 mm in diameter drilled into bottom of each well used, and each well containing a disk of 8 mm diameter Whatman FTA filter paper. Samples subjected to lysis buffer are filtered with centrifugation.

Advantage:

DNA Quantification

After DNA extraction, an accurate measurement of the amount and quality of DNA extract is desirable. When the correct amount of DNA is added to PCR, it results in best quality within short duration of time. Adding less or more amount of DNA will results in a profile that is difficult or impossible to interpret. 40

Quantity of DNA that can be extracted from a sample depends on the type of model. Quantity of DNA in different biological samples is shown in Table 1 . 42

Table 1

Type of sample

Amount of DNA

Liquid blood

30,000 ng/mL

Stain of blood

200 ng/cm ²

Liquid saliva

5,000 ng/mL

Hair (with root) shed

1-12 ng/root

Hair (with root) plucked

1-750 ng/root

Liquid semen

250,000 ng/mL

Postcoital vaginal swab

0-3,000 ng/swab

Oral swab

100-1,500 ng/swab

Urine

1-20 ng/mL

Bone

3-10 ng/mg

Tissue

50-500 ng/mg

Classification of Quantification 43

DNA quantification can be classified as follows:

1. Nonnucleic acid-based quantification methods.

Microscopic and macroscopic examination.

Chemical and immunological methods.

2. DNA-based total genomic methods.

Intact and degraded DNA-UV spectrometry.

○ PicoGreen homogenous microtiter plate assays.

Intact vs degraded DNA-agarose gel electrophoresis.

3. Real-time PCR, DNA-based target specific methods.

Human total autosomal DNA.

Y chromosome DNA, mitochondrial DNA (mt-DNA), Alu repeat real-time PCR.

4. End-point PCR DNA quantification and alternative DNA detection methods.

5. RNA-based quantification.

Visualization on agarose gels

Advantages:

It is relatively easy and quick method for assessing both quality and quantity of extracted DNA.

Gives indication of size of extracted DNA molecules.

Disadvantages:

Quantification is subjective.

Total DNA obtained can be mixture of human DNA and microbial DNA and this can lead to overestimation of DNA concentration. 2

Ultraviolet Spectrometry

Spectrometry is commonly used for quantification of DNA in molecular biology but has not been widely adopted by the forensic community. Usually, DNA absorbs light maximally at 260 nm; this feature is used to estimate the amount of DNA extraction by measuring wavelengths ranging from 220 nm to 300 nm. With this method, it is possible to assess the amount of protein (maximum absorbance is 280 nm) and carbohydrate (maximum absorbance is 230 nm). If the DNA extract is clean, the ratio of absorbance should be between 1.8 and 2.0.

Disadvantages:

Difficult to quantify small amounts of DNA.

It is not human specific. 2

Fluorescence Spectrometry

EtBr or 4′,6 diamidino-2-phenylindole can be used to visualize DNA in agarose gels. In addition to staining agarose gels, fluorescent dyes can be used as an alternative to UV spectrometry for DNA quantification. PicoGreen dye is commonly used because it is specific for double-stranded DNA as it has the ability to detect little amount of DNA as 25 pg/mL.

Disadvantage:

DNA Amplification

There are eight DNA- and RNA-based techniques, but PCR and reverse transcription-PCR have been the predominant techniques.

PCR is the commonly used method of amplification of DNA. PCR amplifies specific regions of DNA template; even a single molecule can be amplified to 1 billion fold by 30 cycles of amplification. 45

DNA amplification occurs in cycling phase, which consists of three stages.

1. Denaturation.

2. Annealing.

3. Extraction.

Normal range of PCR cycle is between 28 and 32; when DNA is very low, then cycles can be increased to 34 cycles. 46

Other methods are as follows: 47

Nucleic acid sequence-based amplification method.

Strand displacement amplification.

Recombinase polymerase amplification.

Strand invasion-based amplification.

Multiple displacement amplification.

Hybridization chain reaction.

After the amplification of DNA, the final step is detection of the DNA-amplified products.

Detection of the DNA-Amplified Products

The following methods are used in forensic human identification:

1. Autosomal short-tandem repeat (STR) profiling

2. Analysis of the Y chromosome

3. Autosomal single-nucleotide polymorphism (SNP) typing.

Autosomal STR Profiling

STRs were discovered in 1980. Since then, they are considered as gold standard in human identification in forensics. STR or microsatellites are the most frequently genotyped to distinguish between individuals. STR consists of mononucleotide, dinucleotide, trinucleotide, tetranucleotide, pentanucleotide, and hexanucleotide repeats of which tetranucleotide repeats are used for genotyping. 2

STR profiling is used in paternity/maternity testing, rape perpetrators' identification, kinship testing, and disaster victim identification. 48

STR-based DNA analysis in forensic has been well accepted by professionals and population as an important tool in criminal justice and in human identification.

Advantages:

The test is simple.

Analysis of the Y Chromosome

Typically, biologically a male individual has 1 Y chromosome and contains 55 genes. Because of this unique feature, analysis of Y chromosome is done in crime cases. 50

Application of Y chromosome in forensic medicine: It is present only in males. Thus, in crime cases, the investigators expect to find Y chromosome at the crime scene. Also, when talking about male-female ratio in body fluid mixtures, such as sexual assault or rapes, by analyzing the Y-STR component, the investigators can obtain more information regarding the male component. It is well known that azoospermic or vasectomized rapists do not leave semen traces, and it is impossible to find spermatozoa on the microscopic examination. In such cases, the Y-STR profiling is very useful, offering information regarding the identity of the accused person. 50

Analysis of Mitochondrial DNA (mt-DNA)

mt-DNA is inherited from mother; thus all the members of a matrilineal family share the identical haplotype.

Advantages:

mt-DNA has 200 to 1,700 copies per cell.

Increased probability of survival when compared to nuclear DNA.

Applications:

Analysis of biologic samples that are severely degraded or old.

Samples with low amount of DNA (e.g., hair shafts). 51

Autosomal Single-Nucleotide Polymorphism Typing

SNP has a lower heterozygosity when compared with STRs. Advantage of SNP typing over STR is that the DNA template size can be as large as 50 BPs, compared with STRs that need a size of 300 BPs to obtain good STR profiling. 52 Due to this reason, SNP has become an important tool in analyzing degraded samples. Thus in the 2001 World Trade Center disaster, victims were identified using SNP typing. 53 54

Impact of Genetic Identification in Justice 1

Genetic testing using DNA has been widely applicable to the field of justice. This method is being used for the following:

Identification of accused and confirmation of guilt.

Exculpation of innocent ones.

Identification of persons who commit crimes or serial killers.

Identification of victims in disasters.

Establishing consanguinity in complex cases.

Conclusion

Currently, the DNA genotyping of all types of microtraces or biological traces containing nucleated cells is possible if they are not entirely demolished, either chemically or by bacteria. The DNA analysis is an important tool in solving caseworks in forensic medicine, such as establishing the custody of a child through paternity or maternity tests, identifying victims from crimes or disasters, or exonerating innocent people convicted to prison.

Footnotes

Conflict of Interest None declared.

References

1. Dumache R, Ciocan V, Muresan C, Enache A.Molecular genetics and its applications in forensic sciences London: Intech; 2016: chap. 5. [ Google Scholar]

2. Goodwin W, Linacre A, Hadi S. Chichester: John Wiley & Sons; 2011. An Introduction to Forensic Genetics. [ Google Scholar]

23. Cseke L J, Kirakosyan A, Kaufman P B, Westfall M V. Boca Raton, FL: CRC Press; 2011. Handbook of Molecular and Cellular Methods in Biology and Medicine. [ Google Scholar]

27. inventors; Becton Dickinson and Co, assignee Woodard D L, Howard A J, Down J A.Process for purifying DNA on hydrated silica. United States Patents. [Patent no.: US 5,342,931]:1994

29. Doyle J. Berlin/Heidelberg: Springer; 1991. DNA protocols for plants; pp. 283-293. [ Google Scholar]

31. Elkins K. Kidlington, England: Oxford Academic Press; 2013. Forensic DNA Biology; pp. 43-45. [ Google Scholar]

34. inventor; Whitehead Institute for Biomedical Research, assignee Hawkins T.DNA purification and isolation using magnetic particles. United States Patents. [Patent no.: US 5,705,628]:1998

35. Elkins K. Kidlington, England: Oxford Academic Press; 2013. Forensic DNA Biology; pp. 43-45. [ Google Scholar]

37. Fomovskaia G, Smith M A, Davis J C, Jones K, Fomovsky M A. inventors; WhatmanInc, assignee . FTA-coated media for use as a molecular diagnostic tool. United States patent US 6,746,841. 2004.

40. Hui X, Liqun X, Jiayi C.Method for rapidly extracting nucleic acid from biological sample2014. China

Articles from Global Medical Genetics are provided here courtesy of Thieme Medical Publishers

# data[].attributes.attachment_link.title
DNA Profiling in Forensic Science: A Review

# data[].attributes.attachment_link.description
DNA is present in most of the cells in our body, which is unique in each and every individual, and we leave a trail of it everywhere we go. This has become an advantage for forensic investigators who use DNA to draw conclusion in identification of victim ...

# data[].attributes.body
To be honest, I’m only going to read half of this since it’s a 32-page article.

Back in 1995, the National Institute of Justice (NIJ) started looking into how DNA could help clear people who were wrongfully convicted. This led to the creation of the National Commission on the Future of DNA Evidence, with the goal of improving how DNA is used in the criminal justice system. The Commission was led by Chief Justice Shirley S. Abrahamson and included members from all parts of the justice system. They focused on crime scene investigations, evidence collection, and the growing use of DNA technology to solve old cases, including those through the Combined DNA Index System (CODIS).

The rise of DNA databases and advancements in DNA technology have completely changed how criminal investigations are done. Initially, these databases were only used for violent crimes, but now they include profiles of all convicted felons, making them much more effective. New legal tactics, like "John Doe" warrants based on DNA profiles, allow authorities to keep cases open until they find a match. Technologies like PCR and STR have made it possible to analyze smaller or even degraded samples from cold cases, and CODIS helps connect crimes across different states by matching DNA profiles.

Y-chromosome analysis is another forensic tool that focuses on male-specific genetic markers, which is particularly helpful in cases where there are multiple male contributors to a biological sample. Since the Y-chromosome is passed from father to son, it can also be used to trace male family relationships. This technique might reduce the need to separate biological cells in evidence like rape kits. However, DNA profiles from Y-chromosome testing don’t work with CODIS, which mainly uses STR analysis for its database. Collaboration with crime labs is essential to figure out the best approach for each case.

# data[].attributes.body
The article explains how advances in DNA technology have revolutionized crime-solving by allowing investigators to accurately identify or exonerate suspects through DNA evidence. DNA from crime scenes can be compared to that of identified suspects or cross-checked with DNA databases like CODIS to find matches, even in cold cases or when no suspects are initially known. This technology has helped solve numerous crimes, prevent wrongful convictions, and link offenders to multiple cases.

I think this article gave some very good and precise example on how DNA can help us investigate crime cases, and delves deep into the details behind getting the tech necessary in order to use DNA in this manor. I strongly encourage reading this article.

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TOC | Executive Summary | Using DNA to Protect the Innocent

USING DNA TO SOLVE CRIMES

The past decade has seen great advances in a powerful criminal justice tool: deoxyribonucleic acid, or DNA. DNA can be used to identify criminals with incredible accuracy when biological evidence exists. By the same token, DNA can be used to clear suspects and exonerate persons mistakenly accused or convicted of crimes. In all, DNA technology is increasingly vital to ensuring accuracy and fairness in the criminal justice system.

News stories extolling the successful use of DNA to solve crimes abound. For example, in 1999, New York authorities linked a man through DNA evidence to at least 22 sexual assaults and robberies that had terrorized the city. In 2002, authorities in Philadelphia, Pennsylvania, and Fort Collins, Colorado, used DNA evidence to link and solve a series of crimes (rapes and a murder) perpetrated by the same individual. In the 2001 "Green River" killings, DNA evidence provided a major breakthrough in a series of crimes that had remained unsolved for years despite a large law enforcement task force and a $15 million investigation.

DNA is generally used to solve crimes in one of two ways. In cases where a suspect is identified, a sample of that person's DNA can be compared to evidence from the crime scene. The results of this comparison may help establish whether the suspect committed the crime. In cases where a suspect has not yet been identified, biological evidence from the crime scene can be analyzed and compared to offender profiles in DNA databases to help identify the perpetrator. Crime scene evidence can also be linked to other crime scenes through the use of DNA databases.

For example, assume that a man was convicted of sexual assault. At the time of his conviction, he was required to provide a sample of his DNA, and the resulting DNA profile was entered into a DNA database. Several years later, another sexual assault was committed. A Sexual Assault Nurse Examiner worked with the victim and was able to obtain biological evidence from the rape. This evidence was analyzed, the resulting profile was run against a DNA database, and a match was made to the man's DNA profile. He was apprehended, tried, and sentenced for his second crime. In this hypothetical case, he was also prevented from committing other crimes during the period of his incarceration.

DNA evidence is generally linked to DNA offender profiles through DNA databases. In the late 1980s, the federal government laid the groundwork for a system of national, state, and local DNA databases for the storage and exchange of DNA profiles. This system, called the Combined DNA Index System (CODIS), maintains DNA profiles obtained under the federal, state, and local systems in a set of databases that are available to law enforcement agencies across the country for law enforcement purposes. CODIS can compare crime scene evidence to a database of DNA profiles obtained from convicted offenders. CODIS can also link DNA evidence obtained from different crime scenes, thereby identifying serial criminals.

In order to take advantage of the investigative potential of CODIS, in the late 1980s and early 1990s, states began passing laws requiring offenders convicted of certain offenses to provide DNA samples. Currently all 50 states and the federal government have laws requiring that DNA samples be collected from some categories of offenders.

When used to its full potential, DNA evidence will help solve and may even prevent some of the Nation's most serious violent crimes. However, the current federal and state DNA collection and analysis system needs improvement:

(1)

In many instances, public crime labs are overwhelmed by backlogs of unanalyzed DNA samples.

(2)

In addition, these labs may be ill-equipped to handle the increasing influx of DNA samples and evidence. The problems of backlogs and lack of up-to-date technology result in significant delays in the administration of justice.

(3)

More research is needed to develop faster methods for analyzing DNA evidence.

(4)

Professionals working in the criminal justice system need additional training and assistance in order to ensure the optimal use of DNA evidence to solve crimes and assist victims.

President Bush believes we must do more to realize the full potential of DNA technology to solve crime and protect the innocent. Under the President's initiative, the Attorney General will improve the use of DNA in the criminal justice system by providing funds and assistance to ensure that this technology reaches its full potential to solve crimes.

1. Eliminating Backlogs Top

One of the biggest problems facing the criminal justice system today is the substantial backlog of unanalyzed DNA samples and biological evidence from crime scenes, especially in sexual assault and murder cases. Too often, crime scene samples wait unanalyzed in police or crime lab storage facilities. Timely analysis of these samples and placement into DNA databases can avert tragic results. For example, in 1995, the Florida Department of Law Enforcement linked evidence found on a rape-homicide victim to a convicted rapist's DNA profile just eight days before he was scheduled for parole. Had he been released prior to being linked to the unsolved rape-homicide, he may very well have raped or murdered again.

By contrast, analysis and placement into CODIS of DNA profiles can dramatically enhance the chances that potential crime victims will be spared the violence of vicious, repeat offenders. The President's initiative calls for $92.9 million to help alleviate the current backlogs of DNA samples for the most serious violent offenses - rapes, murders, and kidnappings - and for convicted offender samples needing testing. With this additional federal backlog reduction funding, the funding provided by this initiative to improve crime laboratory capacity, and continued support from the states, the current backlogs will be eliminated in five years.
Understanding the Backlog
The state and local backlog problem has two components: (1) " casework sample backlogs," which consist of DNA samples obtained from crime scenes, victims, and suspects in criminal cases, and (2) " convicted offender backlogs, " which consist of DNA samples obtained from convicted offenders who are incarcerated or under supervision. The nature of the DNA backlog is complex and changing, and measuring the precise number of unanalyzed DNA samples is difficult.

Casework Sample Backlogs: In a 2001 survey of public DNA laboratories, the Bureau of Justice Statistics (BJS) found that between 1997 and 2000, DNA laboratories experienced a 73% increase in casework and a 135% increase in their casework backlogs. Many casework samples go unanalyzed for lack of a suspect to which to compare the biological evidence from the crime scene. These are often referred to as "no-suspect" cases. Based on an ongoing assessment of crime laboratories and law enforcement agencies, the National Institute of Justice (NIJ) estimates that the current backlog of rape and homicide cases is approximately 350,000. The initiative calls for $76 million in FY 2004 to help eliminate these backlogs over five years.

Convicted Offender Backlogs:States are increasing the number of convicted offenders required to provide DNA samples. Currently, 23 states require all convicted felons to provide DNA samples. Preliminary estimates by NIJ place the number of collected, untested convicted offender samples at between 200,000 and 300,000. NIJ also estimates that there are between 500,000 and 1,000,000 convicted offender samples that are owed, but not yet collected. The initiative calls for $15 million in FY 2004 to help eliminate convicted offender backlogs over five years.

The federal government also faces a high demand for analysis of casework and convicted offender DNA samples. The FBI has two DNA casework analysis units (see page 5). The first unit, which focuses on analyzing nuclear DNA, has a backlog of approximately 900 cases. The second unit, which focuses on analyzing mitochondrial DNA (mtDNA), has a backlog of roughly 120 cases.

The federal government also collects DNA samples from persons convicted of offenses in certain categories, including crimes of violence or terrorism. The FBI currently has a backlog of approximately 18,000 convicted offender samples. The initiative calls for $1.9 million in FY 2004 to fund the federal convicted offender program; some of these funds will be devoted to eliminating the federal convicted offender backlog.
Effect of Clearing the Backlog
The results of addressing backlogs are dramatic, as the two examples below illustrate:

In September 1993, a married couple was attacked on a jogging trail in Dallas by a man with a gun who sexually assaulted the woman after shooting the man. No suspect was ever positively identified, although police investigated over 200 leads and 40 potential suspects. In August 2000, evidence from the case was analyzed using current DNA technology. Then, in February 2001, the DNA sample was matched to an individual who was already serving a five-year sentence for an unrelated 1997 sexual assault of a child. The man has since been convicted of capital murder and aggravated sexual assault.

In March 1992, an Alexandria, Virginia shop owner was stabbed more than 150 times in her home. There were no witnesses to the crime. For years, detectives had no leads, but they did have traces of someone's blood, apparently from the fierce struggle between the victim and the killer. Meanwhile, in 1996, a man pleaded guilty to robbing a gas station, and his DNA was collected for analysis and inclusion in the Virginia DNA database. Because of the backlog, the man's sample was not immediately analyzed. In the summer of 2000, the sample was analyzed and matched through the database to the evidence from the Alexandria woman's murder. In April 2001, almost nine years after the commission of this brutal crime, the man was sentenced to life in prison.

Several law enforcement agencies, prosecutors' offices, and crime labs across the country have established innovative programs to review old cases. Often called "cold case units," these programs have enabled criminal justice officials to solve cases that have languished for years without suspects. Most frequently, DNA evidence has been the linchpin in solving these cases. For instance, this past July, a California man was found guilty of the 1974 rape-homicide of a 19 year-old pregnant woman - a case that was solved through DNA evidence nearly thirty years after the crime was committed.
Prior Federal Support of State DNA Backlog Reduction
In recent years, the federal government has strongly supported states in their efforts to eliminate backlogs of convicted offender and casework DNA samples. Since the creation in 2000 of the Department of Justice's (DOJ's) Convicted Offender DNA Backlog Reduction Program, more than 493,600 offender samples from 24 states have been analyzed. Since the creation in 2001 of the No Suspect Casework DNA Backlog Reduction Program, federal funds have been provided to support the analysis of approximately 24,800 cases. States have analyzed evidence in an additional 18,000 "no-suspect" cases as a result of a match requirement of Convicted Offender DNA Backlog Reduction funding.

In 2002 and 2003 combined, the President requested and Congress appropriated $70.8 million to fund these DNA backlog reduction programs. Additionally, Attorney General John Ashcroft also made available $25 million in Asset Forfeiture funds to address the backlog of convicted offender and "no suspect" casework samples. Thus, the Bush Administration already has devoted more than $95 million to reducing DNA backlogs.

2. Strengthening Crime Laboratory Capacity Top

At present, many of our Nation's crime laboratories do not have the capacity necessary to analyze DNA samples in a timely fashion. Many have limited equipment resources, outdated information systems, and overwhelming case management demands. As a result, the criminal justice system as a whole is unable to reap the full benefits of DNA technology. The President's initiative will provide federal funding to further automate and improve the infrastructure of federal, state, and local crime labs so they can process DNA samples efficiently and cost-effectively. These infrastructure improvements are critical to preventing future DNA backlogs, and to helping the criminal justice system realize the full potential of DNA technology.
Increasing the Analysis Capacity of Public Crime Labs
The President's initiative will provide significant support to public crime labs so that these labs can update their infrastructure, automate their DNA analysis procedures, and improve their retention and storage of forensic evidence. The initiative calls for $60 million in FY 2004 funding, which will be dedicated to:

Providing Basic Infrastructure Support: Some public crime laboratories still need assistance to help them obtain equipment and material to conduct the basic processes of DNA analysis - extraction, quantitation, amplification and analysis - and to help them meet various accreditation requirements.

Building Infrastructure through Laboratory Information Management Systems: Laboratory Information Management Systems, or "LIMS," are designed to automate evidence handling and casework management, to improve the integrity and speed of evidence handling procedures, and to ensure proper chain of custody. DOJ estimates that only 10 percent of the public DNA laboratories have LIMS systems.

Providing Automation Tools to Public DNA Laboratories:To streamline aspects of the DNA analysis procedure that are labor and time-intensive, crime laboratories should have automated systems, such as robotic DNA extraction units. Automated DNA analysis systems increase analyst productivity, limit human error and reduce contamination.

Providing Support for the Retention and Storage of Forensic Evidence: Forensic evidence must be stored in a manner that ensures its integrity and maintains its availability throughout criminal investigations and judicial proceedings. Appropriate evidence storage conditions require costly equipment such as security systems, environmental control systems, ambient temperature monitors, and de-humidifiers. The initiative will support the improvement of evidence storage capabilities.

Funding the FBI Forensic Analysis Programs
The FBI Laboratory runs several different programs for the analysis of DNA information. The Nuclear DNA Program supports federal, state, local, and international law enforcement agencies by providing advanced technical assistance within the forensic biology discipline and sub-disciplines through interrelated capabilities and expertise. The Mitochondrial DNA (mtDNA) Analysis Program is responsible for performing mtDNA analysis of forensic evidence containing small or degraded quantities of DNA on items of evidence submitted from federal, state, and local law enforcement agencies. Mitochondrial DNA is a powerful tool available for investigating cases of kidnapping, missing persons, and skeletal remains where nuclear DNA is not present. The initiative will provide funds to these two existing programs to permit them to continue their important work. In addition, the initiative will provide funds to the FBI to further expand regional mtDNA labs that will provide an alternative source for mtDNA analysis to state and local law enforcement, and allow the FBI laboratory to concentrate more of its efforts on federal cases. The initiative calls for $20.5 million in FY 2004 to fund these programs.
Funding the Combined DNA Index System
The Combined DNA Index System (CODIS), administered by the FBI, maintains DNA profiles obtained through federal, state, and local DNA sample collection programs, and makes this information available to law enforcement agencies across the country for law enforcement identification purposes. Currently, the National DNA Index System (NDIS) of CODIS contains about 1.7 million DNA profiles. The President's initiative includes funding to complete a general redesign and upgrade of CODIS, which will increase the system's capacity to 50 million DNA profiles, reduce the search time from hours to microseconds for matching DNA profiles, and enable instant, real‑time (as opposed to weekly) searches of the database by participating forensic laboratories. The initiative calls for $9.9 million in FY 2004 to fund this program.

3. Stimulating Research And Development Top

In order to improve the use of DNA technology to advance the cause of justice, the Attorney General will stimulate research and development of new methods of analyzing DNA samples under the President's initiative. Also, the President has asked the Attorney General to establish demonstration projects under the initiative to further study the public safety and law enforcement benefits of fully integrating the use of DNA technology to solve crimes. Finally, the President has directed the Attorney General to create a National Forensic Science Commission to study rapidly evolving advances in all areas of the forensic sciences and to make recommendations to maximize the use of the forensic sciences in the criminal justice system. In all, the President's initiative will devote $24.8 million in FY 2004 to fund advances in the use of DNA technology.
Improving DNA Technology
Forensic DNA analysis is rapidly evolving. Research and development of tools that will permit crime laboratories to conduct DNA analysis quickly is vital to the goal of improving the timely analysis of DNA samples. Smaller, faster, and less costly analysis tools will reduce capital investments for crime laboratories while increasing their capacity to process more cases. Over the course of the next several years, DNA research efforts will focus on the following areas:

The development of "DNA chip technology" that uses nanotechnology to improve both speed and resolution of DNA evidence analysis. This technology will reduce analysis time from several hours to several minutes and provide cost-effective miniaturized components.

The development of more robust methods to enable more crime labs to have greater success in the analysis of degraded, old, or compromised items of biological evidence.

Advanced applications of various DNA analysis methods, such as automated Short Tandem Repeats (STRs), Single Nucleotide Polymorphisms (SNPs), mitochondrial DNA analysis (mtDNA), and Y-chromosome DNA analysis.

The use of animal, plant, and microbial DNA to provide leads that may link DNA found on or near human perpetrators or victims to the actual perpetrator of the crime.

Technologies that will enable DNA identification of vast numbers of samples occasioned by a mass disaster or mass fatality incident.

Technologies that permit better separation of minute traces of male sexual assailant DNA from female victims.

The initiative devotes $10 million in FY 2004 funding to benefit the state and local criminal justice community through DNA research and development. It also requests $9.8 million in FY 2004 funding to further expand the FBI's DNA research and development program.
Establishing DNA Demonstration Projects
To further research the impact of increased DNA evidence collection on public safety and law enforcement operations, the Attorney General will conduct rigorous scientific research through demonstration projects on the use of DNA evidence under the initiative. This research will help determine the scope of public safety benefits that result when police are trained to more effectively collect DNA evidence and prosecutors are provided with training to enhance their ability to present this evidence in court.

Several jurisdictions will be selected to incorporate core training and evidence collection requirements in their daily operations. At each site, one or more law enforcement agencies will be chosen to implement extensive training on the collection of DNA evidence and to increase the resources devoted to the investigation and prosecution of these cases. Prosecutors will also receive training on how to more effectively present DNA evidence and how forensic DNA technology may be used to solve current and "cold" cases. Jurisdictions that received increased training and resources will be compared with jurisdictions that did not receive these benefits.

The resulting comparison will measure the impact of increased DNA evidence collection on public safety and law enforcement operations. For example, projects will examine whether there are increased crime clearance rates, whether DNA aided investigations, the number of cases successfully prosecuted, the number of cases where guilty pleas were obtained due to the presence of DNA evidence, any financial savings resulting from the use of forensic evidence, and increased responsiveness to victims. The information obtained will allow state and local governments to make more informed decisions regarding investment in forensic DNA as a crime-fighting tool. The initiative calls for $4.5 million in FY 2004 to fund these projects.
Creating a National Forensic Science Commission
To facilitate the ability of policymakers to assess the needs of the forensic science community, and to stimulate public awareness of the uses of forensic technology to solve crimes, the President has directed the Attorney General to create a National Forensic Science Commission. The Commission will be charged with two primary responsibilities: (1) developing recommendations for long-term strategies to maximize the use of current forensic technologies to solve crimes and protect the public, and (2) identifying potential scientific breakthroughs that may be used to assist law enforcement.

The Attorney General will appoint Commission members from professional forensic science organizations and accreditation bodies and from the criminal justice community. These individuals will have broad knowledge and in-depth expertise in the criminal justice system and in various areas of the forensic sciences such as analytical toxicology, trace evidence, forensic biology, firearms and toolmark examinations, latent fingerprints, crime scene analysis, digital evidence, and forensic pathology, in addition to DNA. Judges, prosecutors, attorneys, victim advocates, and other members of the criminal justice system will also be represented on the Commission.

The Commission will study advances in all areas of the forensic sciences and make recommendations on how new and existing technologies can be used to improve public safety. The Commission will also serve as an ongoing forum for discussing initiatives and policy, and may issue recommendations that will assist state and local law enforcement agencies in the cost-effective use of these technologies to solve crimes. The initiative devotes $500,000 in FY 2004 to the establishment of the Commission.

4. Training the Criminal Justice Community Top

In order to maximize the use of DNA technology, under the President's initiative, the Attorney General will develop training and provide assistance regarding the collection and use of DNA evidence to the wide variety of professionals involved in the criminal justice system, including police officers, prosecutors, defense attorneys, judges, forensic scientists, medical personnel, victim service providers, corrections officers, and probation and parole officers.

Key players in the criminal justice system should receive additional training in the proper collection, preservation, and use of DNA evidence. Fundamental knowledge of the capabilities of DNA technology is essential for police officers to collect evidence properly, prosecutors and defense attorneys to introduce and use it successfully in court, and judges to rule correctly on its admissibility. Victim service providers and medical personnel likewise need to understand DNA technology in order to encourage more successful evidence collection and to be fully responsive to the needs of victims.
Law Enforcement Training
As the first responders to crime scenes, law enforcement officers should be able to identify, collect and preserve probative biological evidence for submission to crime laboratories. Improper collection can mean that valuable evidence is missed or rendered unsuitable for testing. The initiative devotes $3.5 million in FY 2004 to assist law enforcement in meeting the following training needs:

Basic "awareness training" on DNA evidence for patrol officers and other first-responders;

Intensive training on identifying, collecting, and preserving potential DNA evidence for evidence technicians, investigators, and others processing crime scenes;

Training and education for investigators and responding officers on DNA databases and their potential to provide leads in current and "cold" cases; and

Training and information for law enforcement leadership and policymakers to facilitate more informed decisions about effective DNA evidence collection and testing.

Training Prosecutors, Defense Attorneys, and Judges
In order to achieve just results in cases involving DNA evidence, prosecutors, defense attorneys, and judges should receive proper training on the use and presentation of DNA evidence. The initiative devotes $2.5 million in FY 2004 to support:

Training and technical assistance for prosecutors to learn about solving "cold cases" with DNA evidence, responding to post-conviction DNA testing requests, and developing innovative legal strategies to optimize the power of forensic DNA technology. Grant funds will beavailable for state and local prosecutors' organizations for the development and delivery of training materials to assist prosecutors in presenting this evidence before courts and juries, and in understanding more about the value of DNA evidence in particular cases.

Training for defense counsel handling cases involving biological evidence on the applications and limitations of DNA evidence. Grant funds will be made available to continuing legal education programs or bar associations to provide training and resources on forensic DNA technology.

Training for judges, who must be equipped with sufficient technical and scientific knowledge to make appropriate rulings in cases involving DNA evidence. Grant funds will be available to national judicial conferences and organizations.

Training For Probation and Parole Officers and Corrections Personnel
Probation and parole officers play a critical role in ensuring that offenders are complying with their statutory obligations to provide DNA samples. Corrections personnel often are responsible for obtaining DNA samples from inmates required by law to submit such samples. Through training and education programs, these professionals will be better equipped to ensure that samples are taken from all individuals who are required by law to provide them. The initiative calls for $1 million in FY 2004 to support this training.
Training for Forensic Scientists
The forensic science community has a critical need for trained forensic scientists in public crime laboratories. The initiative will assist the development of comprehensive training programs for a new generation of forensic scientists, enabling new forensic scientists to receive in-depth training to prepare them for analyzing actual casework in a crime laboratory. The initiative calls for $3 million in FY 2004 to support this training.
Training for Medical Personnel
The initiative will also provide $5 million in FY 2004 to support the development of training and educational materials for doctors and nurses involved in treating victims of sexual assault. Trained medical personnel are needed to effectively collect usable DNA evidence, while safeguarding the privacy rights and addressing the needs of rape victims requiring sexual assault exams. These programs will specifically target underserved areas of the country. Funding may also be used to support the development of SANE (Sexual Assault Nurse Examiner), SAFE (Sexual Assault Forensic Examiner), and SART (Sexual Assault Response Team) programs.
Training for Victim Service Providers
Victims and those who advocate on their behalf must have access to information about the investigative and courtroom uses of forensic DNA evidence. Victims should be properly informed about how DNA evidence may impact their cases. In situations involving post-conviction DNA testing, victim service providers must be able to assist victims through the often-painful process of newly-ordered DNA tests and re-opened court proceedings. To address the concerns of victims, the initiative would develop additional DNA education and training programs for victim advocates and victim service providers so that they may better assist victims in all cases involving DNA evidence. The initiative calls for $5 million in FY 2004 to support this training.

TOC | Executive Summary | Using DNA to Protect the Innocent

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ADVANCING JUSTICE THROUGH DNA TECHNOLOGY: USING DNA TO SOLVE CRIMES

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TOC | Executive Summary | Using DNA to Protect the Innocent The past decade has seen great advances in a powerful criminal justice tool: deoxyribonucleic acid, or DNA. DNA can be used to identify criminals with incredible accuracy when biological evidence exists.

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The History of DNA: From Crime Scenes to Consumer Goods

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The History of DNA: From Crime Scenes to Consumer Goods

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The first identification of DNA was in 1860s but DNA was only recognized as a 3 dimensional double helix in 1953. By the 1980s DNA was used in labs to establish paternity and by 1984, Alec Jeffreys had discovered how to match fingerprints. Two years later he was asked to aid in the first murder case using fingerprints and DNA analysis. In 1986 there was a brutal murder of two people, a mentally challenged boy was accused of the crime and even confessed, but when the poliec hired Alec to test his DNA he found that the boy was innocent. He then went around the town taking DNA samples and eventually matched the DNA in the crime scene to the town baker. This was one of the first times DNA was used to accurately solve a homicide case and paved the way for the next 4 decades. In today's age our knowledge about DNA and how it works has grown immensely. There are now databases of millions of people's DNA. And the first case solved by DNA genealogy was in 2018, tracking the victims family and eventually catching the culprit. This article sums up the history and future uses of DNA forensics and also touches upon the possible risks of the use of DNA. A case that proves this was one where a postal worker was put on death row because they found the DNA of the victim in his fingernails, but it turned out it was just an unfortunate circumstance and he was in fact innocent. In conclusion, the article shows how DNA can help us not only solve crimes but do so much more.

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Since the first use of DNA in a 1986 criminal case, science and technology have opened additional doors of opportunity to employ DNA in the legal field and beyond. Today, DNA not only helps place suspects at crime scenes, but it also enables forensic genealogists to solve cases that went cold decades ago. Many people see DNA as usable only for criminal investigations and, in some cases, medical studies, but modern technology has also allowed both researchers and practitioners in many fields to use DNA as a consumer good. The history of DNA use began in a courtroom, but it's moving into counselor's offices, food labs and archives.

The future of DNA research and application offers exciting opportunities, as well. For instance, Dr. Francis Collins, the physician-geneticist who led the Human Genome Project to map human DNA, remarked in an interview on PBS that:

Cancer is a disease of the genome. And that's what happens. You make mistakes in a cell somewhere in your body that causes it to start to grow when it should've stopped, and that's cancer. And those mistakes are mistakes of DNA.

Does finding the cure for cancer lie in DNA? Probably. And therefore, it rests in the hands of DNA professionals.

In this article, we cover the transition from DNA as a tool for criminal investigation to DNA as a consumer good. To recognize what's possible in the future, first take a look at the history of DNA.

The History of DNA

Swiss chemist Friedrich Miescher first identified DNA in the 1860s, but it wasn't until 1953 that James Watson and Francis Crick, a biologist and a physicist respectively, recognized that DNA exists as a three-dimensional double helix. After that, DNA research and its applications began to accelerate. By the 1980s, labs were using DNA to establish paternity in questioned cases. In 1986, investigators asked a young geneticist named Alec Jeffreys, who two years earlier had developed the genetic fingerprint, to assist with solving a murder case. Jeffreys' research was already helping establish evidence in other legal matters, so why not try it on the most hideous crime of all?

Two 15-year-old girls had been sexually assaulted and murdered. A teenage male with learning difficulties stood accused of the crime. In fact, he confessed to one murder but not both. Hoping to pin both killings on the boy, police hired Jeffreys and his team to prove that the teen had done it. They couldn't. In fact, they proved that the boy committed neither crime. Now with no leads, police and Jeffreys began to create genetic profiles of men within the area. When someone reported that a local baker named Colin Pitchfork had boasted that he'd submitted a friend's DNA, police nabbed him. Jeffreys and his team successfully matched Pitchfork's DNA with that found at the crime scene.

Jeffreys' work captured the public's imagination. Even today popular crime procedurals such as CSI and NCIS frequently use DNA evidence as plot twists, making the public and consequently potential jurors aware of the power of DNA. What many people don't know, however, is that it took years of legal wrangling to determine how and when courts would accept DNA evidence. Databases and laboratories had to meet uniform standards. The ethical issues of maintaining databases of felons' DNA had to be wrestled with. And uniform testing procedures had to be established. DNA evidence also helped free several unjustly imprisoned people, giving rise to new areas of concerns and ethical considerations for scientists and lawyers.

As for Jeffreys, the original DNA fingerprint researcher, he went on to study the effects of radiation exposure on DNA. His colleagues in the field also spotted other applications for DNA work, such as mapping the human genome.

In 1990, the Human Genome Project launched. Researchers in this project undertook the mammoth task of mapping a human being's DNA. Within 13 years, the team had completed what it set out to do. The work involved an ethical, legal and social implications (ELSI) program that began to set parameters around DNA research, its uses and its impacts. Collins, the project's head, said in the same piece for PBS:

Let's see what kind of protections we need to put in place so that people don't get injured as a result of what should be a wonderful revolution in medicine and science. The most pressing issue right now - seems like a pedestrian one, but boy, we need to solve it. And that's this issue of genetic discrimination.

While the Human Genome Project was underway, Scottish scientists began experimenting with a much more controversial use of DNA. Cloning. In 1996, researchers at the Roslin Institute cloned a white Dorset Finn sheep they named Dolly. She was the only lamb to survive out of 277 attempts. Before long, fruit flies and mice had had their DNA mapped. And by late in the year 2000, German researchers had mapped the DNA of a 38,000-year-old Neanderthal, opening a massive portal to understanding human origins and evolution.

Scientists also realized the potential of mapping viruses and bacteria, which could give way to new and exciting breakthroughs in healthcare.

What We Can Do with DNA Today

It's been less than 40 years since legal experts first won a case based on DNA evidence. Since then, however, scientific knowledge of and public interest in genetics has flourished. DNA is advancing into new frontiers across a range of industries.

Bioethics

Each of these industrial changes raises a new crop of ethical questions. Creating genealogical databases filled with DNA information could be hacked by bad actors. Genetic counseling could veer into eugenics. Personalized medicine could provide one quality of care for the rich and another for the poor. Biological weapons that target individuals could save lives in some warfare situations but destroy entire ethnicities in others. Bioethicists who work with DNA applications bear a grave responsibility to the future to do their work well.

Bioinformatics

Biological information technology professionals can collect, store and analyze complex biological data to apply to fields such as waste cleanup, climate change, antibiotic resistance, personalized medicine and biological weaponry. Historians can even use DNA to trace the evolutionary history of organisms.

Biological Weaponry

"New genetic-engineering tools are expanding the range of malicious uses of biology and decreasing the amount of time needed to carry them out," reported a study cited in the MIT Technology Review. Though biological warfare conducted at scale dates at least as far back as World War I, using DNA to create weapons that could exploit the genetic differences between ethnicities is thoroughly modern, and it reflects Collins' earlier-mentioned concerns about genetic discrimination. While much of the research and development in biological warfare happens under wraps, militaries and paramilitary groups throughout the world have a strong interest in and capability with DNA-targeting as a weapon of war.

Genealogy

Searching the family tree has evolved into America's second-most popular hobby and second-most-searched internet category, according to USA Today. Genealogy is now a $3 billion per year industry with companies such as Ancestry and MyHeritage leading the way. Inexpensive, easy-to-take and at home genetic testing kits are letting hobbyists discover their great-great-grandparents and beyond. They're also providing the resources for forensic genealogists who are helping law enforcement officials use DNA to track down missing suspects, victims and family members of people involved in crimes. Those DNA results also help identify human remains and notify families about long-lost relatives.

Genetic Counseling

"Genetic counseling is a process to evaluate and understand a family's risk of an inherited medical condition," according to the National Society of Genetic Counselors. "A genetic counselor is a healthcare professional with specialized training in medical genetics and counseling." These professionals conduct research, meet with patients and help make important medical decisions usually in a prenatal, pediatric or cancer environment. Genetic counselors can help identify patterns of genetic conditions in the family in order to equip patients with the knowledge needed to decide on a course of treatment.

Genetic Engineering

Genetic engineers can use DNA to modify the biological structure of an organism, such as a plant grown for human consumption, for example, and improve global diets and food distribution.

Investigations

DNA's value in public investigation goes beyond murder scenes. Investigators can employ DNA to determine paternity, thus helping ensure child support payments or even prosecution for sex crimes.

Personalized Medicine

Personalized medicine matches tailored healthcare to a patient's unique biological makeup. Physicians and other medical care providers create personalized plans using pharmacogenomics, the study of how medicines affect the body. Deep knowledge of DNA lets doctors determine what medicines are right for the individual patient, which ones are most likely to have toxic side effects and which will likely prove ineffective due to a patient's genetic identity.

Uses for DNA has advanced rapidly over the last few decades, and it's likely that its versatility will increase in the future. People looking for exciting careers that make a real-world impact using biology and DNA can find them by preparing for careers in medical science. The convenient online medical laboratory science program from the University of West Florida is designed with working MLT professionals in mind so you can earn your degree and become an MLS while balancing your busy life. After graduation and certification, you'll be prepared for jobs in research and reference labs, blood banks, crime labs and more.

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The History of DNA: From Crime Scenes to Consumer Goods

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Since the first use of DNA in a 1986 criminal case, science and technology have opened additional doors of opportunity to employ DNA in the legal field and beyond. Today, DNA not only helps place suspects at crime scenes, but it also enables forensic genealogists to solve cases that went cold decades ago.

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THE ROLE OF DNA EVIDENCE IN CRIMINAL DEFENSE CASES

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THE ROLE OF DNA EVIDENCE IN CRIMINAL DEFENSE CASES

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This article explains the importance DNA evidence has had on criminal investigations. For instance the article mentions how much of a game changer it has been, and how it has transformed the way cases are defended. One example of how it has changed the defense system, is its impact on organizations like the Innocence Project. The Innocence Project seeks to seeks to exonerate individuals who have been wrongfully convicted. DNA evidence allows for old cases to be reopened, and be new evidence for innocent people to be released from prison. Police stations also often have large DNA databases of known perpetrators, and DNA profiling can help pinpoint individuals who have committed many crimes. DNA analysis has opened the door for more rigorous crime scene investigations with a larger scientific approach.

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The Role of DNA Evidence in Criminal Defense Cases