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1950's
- hair analysis is accepted as a forensic science
1960's
- begins to claim a stronger standard
1970's
- used as evidence to convict people of crimes
1974
- researchers suspect that microscopic hair comparison is completely subjective
1980's
1984
- the FBI confirms that it can not be used to positively match a single individual

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We've all watched television programs like "CSI: Crime Scene Investigation" and "Law and Order." Shows like these simplify the investigative process that investigators conduct in trying to solve the mysteries behind crimes. If you've paid close attention, you may have noticed investigators collecting and examining hair as evidence in crime cases. How is the hair used to solve the crime? The study of the hair follicles found at the scene goes beyond the hair color.

Three layers of the hair shaft are used in determining how a crime was committed and who the criminal may be. The medulla, the innermost core of the hair, can be used to determine the race or ethnicity of the potential perpetrator.

The cortex is the layer over the medulla and is used to compare one hair to another. Microscopic air bubbles and pigment granules help scientists distinguish between the hair types. The outermost layer, the cuticle, can be used to determine the species (if the hair belongs to an animal) through analysis of the patterns of scales that cover the cortex.

In terms of investigation, the root of the hair can be one of the most useful pieces of evidence. By the root (or lack thereof), scientists can tell if the hair was shed naturally, pulled out, or cut off. The root is where investigators can find DNA to help precipitate their analysis. If a hair is pulled out during the anagen phase of the hair growth cycle a root bulb will appear with follicular tissue. This tissue has nuclear DNA which helps create a DNA profile unique to the hair's owner.

During the catagen stage, the root of the hair pulls away from the shaft, and the hair is easily pulled from the head. The root bulb is less round and more elongated in this phase. In the final stage, the telogen phase, the hair sheds naturally and has a club-shaped root bulb. These two phases do not produce a follicular tag, which means nuclear DNA cannot be harvested from hairs in the catagen and telogen phases. However, mitochondrial DNA may be found in just the hair and can help to narrow down subjects, though it cannot distinguish between siblings.

Hair is also useful in chemical tests since it is often the only evidence still remaining after other bodily evidence has disappeared. Scientists can determine the presence of chemicals, poisons, heat treatments, and more. The important thing to note about the use of hair in investigations is that it is only one piece of an investigative puzzle. Hair cannot be used as evidence on its own. However, it can be very useful along with other pieces of evidence. Who knew your hair held so much information?

For more information on healthy hair, hair loss, or hair restoration, contact our office in Atlanta, GA. You can also find us on Facebook and Twitter with the latest in news, hair facts, and more!
Bertino, Anthony J., and Patricia Nolan. Bertino. Forensic Science: Fundamentals & Investigations. Mason, OH: South-Western Cengage Learning, 2009.

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griffin center of hair restoration and research

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hair analysis in crime scene interpretation

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How Do Scientists Use Hair in Crime Scene Investigations?

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We've all watched television programs like "CSI: Crime Scene Investigation" and "Law and Order." Shows like these simplify the investigative process that investigators conduct in trying to solve the mysteries behind crimes. If you've paid close attention, you may have noticed investigators collecting and examining hair as evidence in crime cases.

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On TV, once a forensic expert finds a match for that lone strand of hair at the crime scene, it's over. Finito. The criminal ends up behind bars. And maybe the attorneys exchange some witty banter.

If only science were that straightforward.

Forensic hair analysis used to be a very common tool for the courtroom. Investigators would mount hairs on a microscope slide so as to examine color, thickness and curvature. They'd compare to controls, and then would make conclusions about whether the hair characteristics exclude, or include, certain suspects from consideration. (Hair evidence alone can't ID one specific person.)

That all sounds reasonable. Until you learn that no uniform standards exist for what constitutes a so-called "match", and scientists haven't determined with statistical certainty how frequently different types of hair characteristics occur in the country or the world. If, for example, 25% of the globe has the same kind of hair as what you're looking at in the microscope, that still leaves a lot of suspects.

Inconsistency opens the door to problems. Since 2012, for instance, the elite FBI crime laboratory has been under investigation for overstating hair matches in trials. Even though hair is usually only one of many pieces of evidence in a trial, exaggerated testimony about hair evidence might have contributed to convictions of innocent people.

Then you have the rise of DNA technology, today the gold standard in forensic science. Hair does contain DNA, but hairs found at crime scenes frequently don't have enough DNA to examine, according to forensic chemist Glen P. Jackson, a professor at West Virginia University.

The result is that hair's importance in the courtroom has, shall we say, receded. That's too bad, because hair is about as long-lasting as biological materials come. It lasts for many years and can even be exhumed from graves, long after DNA has degraded, Jackson said at a press conference.

Just think of the cold cases you might solve if hair analysis had a more objective scientific basis. It's no wonder multiple labs are trying to develop new techniques. Jackson talked about his own work this week at a meeting of the American Chemical Society in San Francisco.

Rather than comparing hairs under a microscope, Jackson's team is developing techniques for analyzing hair chemically. A hair shaft is mostly made of a protein called keratin. That keratin protein contains a mixture of 21 amino acids. When you examine the atoms that make up the amino acids, the composition isn't uniform. Atoms come in different isotopes- having the same number of protons but a different number of neutrons. This difference gives isotopes a minuscule difference in mass. Chemists can detect those tiny differences with a technique called mass spectrometry.

Why would a judge and jury care about tiny differences in mass? Because as hair grows, those isotopes keep a record of us. Scientists have known for some time that our diets influence the isotope distribution of all the carbon atoms in hair, because proteins from different sources (plants, versus beef, versus pork) differ in isotope composition.

Jackson's team aims to go further. Could someone's geographic origin affect those isotope numbers? How about age, gender, or body mass index (BMI)? If so, could you use the relative amounts of isotopes in hair to narrow down a suspect's age, sex, or BMI? His team's preliminary studies ( 1, 2, 3) indicate that the answer might be yes.

It's exciting news, but it's important to point out caveats. Here are three. First, Jackson's database of hair donors is very small. To demonstrate that this technique is truly powerful, scientists (and the legal system) need more information about how these isotope makeups vary all over the world.

Second, we're not talking about identifying one specific individual here. At best, this hair technique could provide likely characteristics to investigators. For instance, a hair analysis of this type might conclude it's five times more likely that a suspect is female than male. However, this kind of information is better than nothing. Suppose a hair from a crime scene contains DNA, but there is no match for the sample in the lab's database of individuals. If this hair technique were validated, investigators might have some information about gender, BMI, and age to narrow down a suspect pool.

And finally, this particular hair technology isn't ready for local crime labs. Jackson's work is far from the first application of mass spectrometry in forensic science. But as he explains, the process requires multiple expensive instruments as well as statistical calculations that can be challenging to master.

If further research can demonstrate that isotope analysis of hair is important and valuable, then crime labs are going to want to use it, Jackson says. Only then, he adds, will it make sense to invest resources in streamlining the technique and cutting down its costs.
Disclosure: I am a former employee of Chemical & Engineering News, which is published by the American Chemical Society.

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Forensic Hair Analysis Has A Long Road Back To Courtroom Glory

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On TV, once a forensic expert finds a match for that lone strand of hair at the crime scene, it's over. Finito. The criminal ends up behind bars. And maybe the attorneys exchange some witty banter. If only science were that straightforward. Forensic hair analysis used to be a very common tool for the courtroom.

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Hair analysis has been receiving increased attention during years and, currently, it has become the third most fundamental biological matrix used for ...

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Hair is a common type of evidence submitted to the trace section for analysis. On average, humans shed approximately 100 head hairs per day. Because we are continuously shedding hairs, forensic analysis of hairs is beneficial to the establishment of associations between individuals, a person and an environment, etc. (Example: a questioned hair from a victim's jeans is examined and found to be consistent with the suspect's hair. This examination has provided evidence that an association may have occurred between the suspect and the victim).

A hair is a fibrous outgrowth from the skin of mammals and consists of three anatomical regions, the cuticle, medulla and cortex. Characteristics within these regions are used to determine whether the hair is human or animal, racial origin and body area. A microscopic hair examination can also determine if a hair was forcibly removed, artificially treated or diseased. A comparison microscope can be used to compare a questioned hair to a known hair sample in order to determine if the hairs are similar and if they could have come from a common source.

A questioned hair and known hair sample are viewed, side-by-side, using a comparison microscope in order to determine if they have similar characteristics.

Questioned hair Known hair Comparison Microscope

Hair suitability for DNA examinations

Nuclear DNA analysis can be done on human hairs. The trace section assists the DNA section by screening hairs and determining their suitability for DNA testing. A microscope is used to examine the root end of the hairs, in order to determine if they are suitable. The hair in photo 1 is suitable for nuclear DNA analysis and the hair in photo 2 is not suitable.

Photo 1 Photo 2

If a hair is deemed not suitable for nuclear DNA analysis (ex. no root present or no tissue is attached), it can be sent for mitochondrial DNA testing. A root does not have to present in order for a hair to be suitable for mitochondrial DNA testing.

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Hair is a common type of evidence submitted to the trace section for analysis. On average, humans shed approximately 100 head hairs per day. Because we are continuously shedding hairs, forensic analysis of hairs is beneficial to the establishment of associations between individuals, a person and an environment, etc.

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- two hair strands are compared
- more than 12 factors are monitored
(eg. pigmentation distribution and scale patterns)

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- microscopic hair analysis is usually considered unreliable
- results occasionally contradict those of a DNA test
- much more suiting being used as a tool to narrow a field of investigation, as opposed to using it as evidence to convict a person of a crime

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- the medulla of the hair shaft can be used to identify the race of a person
- the root of the hair shows if the sample was cut, pulled or shed from the head
- the follicle can contain useful DNA for screening

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- hair can be used for preliminary screening of effects of toxic substances in:

air

dust

sediment

food

water

- there is also some experimentation with hair analysis in alternative medicine

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- hair analysis in environmental toxicology can be used as a biological indicator to detect:

long-term heavy metal burden

Mn, Pb, Cr, Cu, Hg, Co, Li, Sr

supplementation in pregnant women

organic pollutants

pesticides

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In recent years hair has become a fundamental biological specimen, alternative to the usual samples blood and urine, for drug testing in the fields of forensic toxicology, clinical toxicology and clinical chemistry. Moreover, hair-testing is now extensively used in workplace testing, as well as, on legal cases, historical research etc. This article reviews methodological and practical issues related to the application of hair as a biological indicator of drug use/abuse or of chronic exposure to environmental toxicants. Hair structure and the mechanisms of drug incorporation into it are commented. The usual preparation and extraction methods as well as the analytical techniques of hair samples are presented and commented on. The outcomes of hair analysis have been reviewed for the following categories: drugs of abuse (opiates, cocaine and related, amphetamines, cannabinoids), benzodiazepines, prescribed drugs, pesticides and organic pollutants, doping agents and other drugs or substances. Finally, the specific purpose of the hair testing is discussed along with the interpretation of hair analysis results regarding the limitations of the applied procedures.

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Franceschin, A, Morosini, L, Dell'Anna, L 1987 Detection of morphine in hair with the Abbott TDXClin Chem.332125
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Robbins, CR 1988Chemical and Physical Behavior of Human HairNew York Springer-Verlag
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SAMHSA 1994HHS. Mandatory guidelines for Federal Workplace Drug Testing Programs.
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Scherer, CR, Reinhardt, G 1995 Nachweis sechs endogener steroide in menschlichen haaren mit GC/MS und isotopenverdünnungsanalyseJahrestagung der Deutschen Gesellschaft für RechtmedizinAlthoff, H 55 Aachen H. Althoff
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Hair as a Biological Indicator of Drug Use, Drug Abuse or Chronic Exposure to Environmental Toxicants - Vassiliki A. Boumba, Kallirroe S. Ziavrou, Theodore Vougiouklakis, 2006

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In recent years hair has become a fundamental biological specimen, alternative to the usual samples blood and urine, for drug testing in the fields of forensic toxicology, clinical toxicology and clinical chemistry. Moreover, hair-testing is now extensively used in workplace testing, as well as, on legal cases, historical research etc.

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Human hair analysis in relation to similar environmental and occupational exposure

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JavaScript is disabled on your browser. Please enable JavaScript to use all the features on this page. * Influence of various factors on elemental composition of human hair was investigated. * Concentrations of chosen elements in hair samples were determined using ICP-TOF-MS. * The obtained results were elaborated using the Statistica ver.

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- hair can be used to detect the usage of:

cocaine

heroin

benzodiazepines (valium, xanax)

amphetamines (methylphenidate)

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- less invasive than obtaining a blood or urine sample
- analysis may be achieved under supervision of law enforcement to ensure genuineness of results
- window of drug detection is weeks, months,sometimes years

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- cosmic treatments (colouring, perming) can interfere
- hair analysis is usually considered controversial, evolving and not standardized

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- hair analysis has many applications, including:

screening of drug addicts

child abuse

drug‐facilitated crimes

sexual assaults under the influence of drug

doping control in sport

workplace drug testing

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- best samples include at least 50 hair shafts

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- pulverization, segmentation into short segments

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- in methanol, acid, sodium hydroxide, buffer, or water solutions

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- liquid/liquid, solid phase, solid phase microextraction

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-  immunoassay screening or chromatography