Trace Evidence by Lindsey https://padlet.com/lindseyscheltema/mff97j4aeuv en-us 2016-03-21 12:09:42 UTC 2017-05-31 15:42:29 UTC hello@padlet.com Trace Evidence from the point of the FBI (Female Body Inspectors) lindseyscheltema https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/105029230 The Trace Evidence Unit (TEU) identifies and compares specific types of trace materials that could be transferred during the commission of a violent crime. These trace materials include human hair, animal hair, textile fibers and fabric, rope, feathers, soil, glass, and building materials. The physical contact between a suspect and a victim can result in the transfer of trace materials. The identification and comparison of these materials can often associate a suspect to a crime scene or with another individual. Physical anthropology (skeletal remains) examinations are also performed. These examinations are conducted to assist in the identification of human remains.

https://www.fbi.gov/about-us/lab/scientific-analysis/trace]]> 2016-04-11 11:28:34 UTC https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/105029230 valariewood https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/105029288 Solved- Trace Evidence]]> 2016-04-11 11:28:58 UTC https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/105029288 Generation of DNA profiles from fabrics without DNA extraction valariewood https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/105029904 Usually when extracting DNA from a surface there is a large chance of contamination because the sample is moved between many vials throughout the process.

This experiment was designed to reduce the number of vial changes and instead of extracting DNA from the cells in the stain, use what is called "free DNA" (DNA that is from already ruptured cells and is floating in solution")

Five different fabrics were chosen and three volunteers (2 male, 1 female) were told to rub the fabric between their thumb and first finger for 5s. A single thumbprint from each volunteer was placed on a glass slide and a swab of the print was taken for PCR amplification.

Near complete profiles were created for each volunteer from the swab, nylon, polyester, and cotton samples. The denim sample created a partial profile.

The experiment was replicated with different volunteers and there was no noticeable difference in the number of alleles that were able to be found on each surface. This shows that the donor is not a dependent factor for the data collection.

Overall the experiment held positive results in such the DNA profiles created without the use of a DNA extraction process were just as good and those created with the extraction process. As such the amended process is cheaper, less chance of contamination, faster, and there is no need to use commercial extraction kits.]]> 2016-04-11 11:32:37 UTC https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/105029904 Touch DNA from hands to glass, fabric, and wood andrew210393 https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/105030525 A study involving 300 volunteers (50% male. 50% female) was undertaken to assess the effectiveness of the recovery of DNA on different surfaces. 

Each material assessed had 100 volunteers handling the material. Material was handled for 60 seconds each before recovery techniques were utilised.

The likelihood of obtaining a profile indicative of the the holder was 9% for glass samples, 23% for fabric samples, and 36% for wood.  There was no significant difference between male and female volunteers.]]> 2016-04-11 11:36:57 UTC https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/105030525 lindseyscheltema https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/105033370 Combinations of different potent technologies (DNA and fingerprints) can be used to solve crime]]> 2016-04-11 11:52:11 UTC https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/105033370 DNA transfer by examination tools - a risk for forensic casework? valariewood https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/106007204 More sensitive DNA systems have made it possible for small amount of transfer DNA to be found within a sample thus contaminating the entire sample. Several reasons for this transfer have been suggested including; DNA on unused gloves, cleaning protocols not working, and speaking without PPE. Tools such as scissor, forceps, and gloves provide the greatest risk of contamination should the cleaning protocol fail.

After the experiment was conducted it was found that the DNA material was transfered between exhibits via the scissors, forceps, and gloves.

To reduce the risk of contamination;
-Encourage awareness amongst staff of the potential sources of contamination within the laboratory and during examination.
-Use of DNA-free scissors, forceps and gloves.
-Preferably use disposable forceps and scissors. When this is impractical, ensure that they have been cleaned prior to reuse using a validated method.
-Clean gloves with an appropriate cleaning agent prior to use.
-Change gloves every time after touching items or surfaces, prior to touching the exhibit.
-Wear multiple layers of gloves to avoid skin exposure during the changing of gloves.
-When touching the exhibit with gloves or forceps, avoid touching areas that are to be targeted for sampling.
]]> 2016-04-15 13:28:21 UTC https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/106007204 Overview of Trace Evidence lindseyscheltema https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/106272310 Fibers, hair, soil, wood, gunshot residue and pollen are only a few examples of trace evidence that may be transferred between people, objects or the environment during a crime. Investigators can potentially link a suspect and a victim to a mutual location through trace evidence. For example, a fiber sample obtained from a suspect's person can be identified through scientific analysis as originating from a garment worn by the victim. The analysis of the fiber evidence can help establish if the victim and suspect were in the same area.

http://www.nij.gov/topics/forensics/evidence/trace/pages/welcome.aspx]]> 2016-04-18 11:31:11 UTC https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/106272310 lindseyscheltema https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/106273130 2016-04-18 11:37:15 UTC https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/106273130 lindseyscheltema https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/106273520 2016-04-18 11:39:50 UTC https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/106273520 lindseyscheltema https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/106273641 2016-04-18 11:40:44 UTC https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/106273641 lindseyscheltema https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/106273763 Trace evidence materials may include:

  • Fibers
  • Primer residue
  • Hairs
  • Paint
  • Duct tape
  • Arson debris
  • Accelerants
  • Fibers
  • Glass
  • Unknown substances

http://www.crimesceneinvestigatoredu.org/trace-evidence-analyst/
]]> 2016-04-18 11:41:44 UTC https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/106273763 lindseyscheltema https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/106273915 Instrumentation commonly used by trace evidence analysts include: stereomicroscopes, polarized light microscopes, glass refractive index measurement devices, scanning electron microscopes, gas chromatography, mass spectrometers, and energy dispersive spectrometers.]]> 2016-04-18 11:42:39 UTC https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/106273915 lindseyscheltema https://padlet.com/lindseyscheltema/mff97j4aeuv/wish/106274033
  • Hair: Hair examinations include determining whether the hair is human or animal. In addition to determining the racial characteristics, body area, length and root type, trace evidence analysts may study hair using mitochondrial DNA testing.
  • Fibers: Fiber analysis may include determining if a fiber is natural or manmade and whether it originated from a specific source.
  • Fabric: Fabric examination includes testing to determine if a known piece of fabric is consistent in color, composition and/or construction and if it can be physically matched to a damaged or torn garment.
  • Mineralogy: The FBI Trace Evidence Unit is one of the only laboratories in the nation that performs geologic services, which includes studying both naturally occurring and manmade geologic materials, such as soil, building materials, gemstones, and glass.
  • Anthropology: Trace evidence often includes forensic anthropology, which includes analyzing human remains in a medico-legal contact.

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