The Evidence: Hair and Fiber
What is Hair and Fiber Evidence?
Hair and Fiber are two of the most important resources in Forensic Science (Claridge). Hair and fibers are the most frequently found and analyzed evidence at a crime scene (Wright). They often provide valuable clues as to an attacker's or assailant's identity (Claridge). Hair and Fibers can support witness statements, connect different areas of a crime scene, and place a suspect at a crime scene (Wright).
Hair Evidence
Hair is defined as the slender outgrowths of the skin of mammals and it is composed mostly of the protein keratin. Hair of various species has characteristic lengths, shape, root appearance, and color. Although different species can be distinguished from each other, hair is considered to be class evidence because of the similarities within the species itself (Deedrick).
Fiber Evidence
Fibers are considered class evidence because they are mass produced. Fibers can be produced from many different sources, and at a crime scene, only the evidence that would not be expected to be there is analyzed. Different properties of fiber include color, material, degree of twist, length, location, thickness, and number of fibers found. Both natural and synthetic fibers exist. 95% of fiber evidence is lost within 24 hours, so it is considered sensitive evidence ("Trace Evidence: Fiber").
Collection of Evidence
Hair and fiber evidence is mainly collected in two stages: at the crime scene and in the autopsy (Claridge). At the crime scene, trace evidence can be collected using tape, tweezers, or by vacuuming an area. Samples are bagged separately in order to prevent cross contamination ("A Simplified Guide to Trace Evidence: How It's Done"). During an autopsy, pathologists scrape the underside of a victim's fingernails for any hairs, fiber, or skin that may have been trapped there (Claridge).
The Case
In a 2007 cold case review of the Stephen Lawrence Murder, a case was formed against two of the suspects, Gary Dobson and David Norris, with new scientific evidence. Mark Ellsion, on the prosecuting side said the new evidence, “consists of the finding of textile fibers, blood and hair linked to Stephen Lawrence on clothing seized from the defendants as part of the original investigation in 1993” (Nelson). This hair and fiber evidence was not originally detectable because of the techniques and practices of the time period (Nelson).
In a re-examination of the clothing found at the time of the murder, investigators found that fragments from Stephen’s red polo shirt had unexpectedly transferred onto his jacket. They then went back to the original sticky tapes found at the crime scene from the suspect’s clothes and found the same red fibers on Gary Dobson's jacket and David Norris's sweatshirt. Investigators also discovered hairs found on David Norris’ jeans that matched the DNA profile of Stephen Lawrence. In the past, the DNA from such a small hair sample would not have been possible, so it was overlooked initially (Cairns).
Breakdown of the Evidence
The Evidence Bag:
A fiber matching those found in Stephen Lawrence's polo shirt was found in the evidence bag debris. The defense did try and argue that the evidence bag could have been contaminated over the years because either the seals had been improperly sealed or because they had failed ("Stephen Lawrence Murder: Dobson and Norris Found Guilty.").
Fiber Tapings:
During the original investigation, samples of fibers were collected using adhesive tape. These samples were reexamined during the cold case review and fibers matching Stephen's polo shirt and jacket were found. The defense tried to argue that Stephen was wearing too many layers of clothing for the fibers from the polo shirt to transfer.
During the original investigation, a cardigan was taken by police from Gary Dobson's room. Blue-green acrylic fibers that matched the wristband and cuff of Stephen's jacket were found on the tapings made from the cardigan. This was considered to be strong evidence by scientists. More common fibers were found on the evidence tapings from Stephen's jacket that could have resembled the cardigan; however, these were more common fibers and so the prosecution did not rely on this evidence. The defense claimed that this cardigan was not something Dobson would wear and was instead kept by the family for decorating and gardening ("Stephen Lawrence Murder: Dobson and Norris Found Guilty.").
Hair Evidence
Hair is defined as the slender outgrowths of the skin of mammals and it is composed mostly of the protein keratin. Hair of various species has characteristic lengths, shape, root appearance, and color. Although different species can be distinguished from each other, hair is considered to be class evidence because of the similarities within the species itself (Deedrick).
Fiber Evidence
Fibers are considered class evidence because they are mass produced. Fibers can be produced from many different sources, and at a crime scene, only the evidence that would not be expected to be there is analyzed. Different properties of fiber include color, material, degree of twist, length, location, thickness, and number of fibers found. Both natural and synthetic fibers exist. 95% of fiber evidence is lost within 24 hours, so it is considered sensitive evidence ("Trace Evidence: Fiber").
Collection of Evidence
Hair and fiber evidence is mainly collected in two stages: at the crime scene and in the autopsy (Claridge). At the crime scene, trace evidence can be collected using tape, tweezers, or by vacuuming an area. Samples are bagged separately in order to prevent cross contamination ("A Simplified Guide to Trace Evidence: How It's Done"). During an autopsy, pathologists scrape the underside of a victim's fingernails for any hairs, fiber, or skin that may have been trapped there (Claridge).
The Case
In a 2007 cold case review of the Stephen Lawrence Murder, a case was formed against two of the suspects, Gary Dobson and David Norris, with new scientific evidence. Mark Ellsion, on the prosecuting side said the new evidence, “consists of the finding of textile fibers, blood and hair linked to Stephen Lawrence on clothing seized from the defendants as part of the original investigation in 1993” (Nelson). This hair and fiber evidence was not originally detectable because of the techniques and practices of the time period (Nelson).
In a re-examination of the clothing found at the time of the murder, investigators found that fragments from Stephen’s red polo shirt had unexpectedly transferred onto his jacket. They then went back to the original sticky tapes found at the crime scene from the suspect’s clothes and found the same red fibers on Gary Dobson's jacket and David Norris's sweatshirt. Investigators also discovered hairs found on David Norris’ jeans that matched the DNA profile of Stephen Lawrence. In the past, the DNA from such a small hair sample would not have been possible, so it was overlooked initially (Cairns).
Breakdown of the Evidence
The Evidence Bag:
A fiber matching those found in Stephen Lawrence's polo shirt was found in the evidence bag debris. The defense did try and argue that the evidence bag could have been contaminated over the years because either the seals had been improperly sealed or because they had failed ("Stephen Lawrence Murder: Dobson and Norris Found Guilty.").
Fiber Tapings:
During the original investigation, samples of fibers were collected using adhesive tape. These samples were reexamined during the cold case review and fibers matching Stephen's polo shirt and jacket were found. The defense tried to argue that Stephen was wearing too many layers of clothing for the fibers from the polo shirt to transfer.
During the original investigation, a cardigan was taken by police from Gary Dobson's room. Blue-green acrylic fibers that matched the wristband and cuff of Stephen's jacket were found on the tapings made from the cardigan. This was considered to be strong evidence by scientists. More common fibers were found on the evidence tapings from Stephen's jacket that could have resembled the cardigan; however, these were more common fibers and so the prosecution did not rely on this evidence. The defense claimed that this cardigan was not something Dobson would wear and was instead kept by the family for decorating and gardening ("Stephen Lawrence Murder: Dobson and Norris Found Guilty.").
Hair Evidence:
In a new search, they found tiny hairs (can be seen to the right) that belonged to Stephen Lawrence (Report).
After being sent to an American forensic lab, a bag that contained a pair of jeans found in Norris' bedroom was found to hold two hairs that matched to Stephen Lawrence. On the cut end of one of the hairs was traces of blood (Nelson).
In a new search, they found tiny hairs (can be seen to the right) that belonged to Stephen Lawrence (Report).
After being sent to an American forensic lab, a bag that contained a pair of jeans found in Norris' bedroom was found to hold two hairs that matched to Stephen Lawrence. On the cut end of one of the hairs was traces of blood (Nelson).
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