Elimination hair and/or fiber samples may need to be obtained from personnel conducting the search.
Prioritize the order of evidence collection. Collect large items first and then proceed to the trace evidence. USE CAUTION WHEN WALKING THE CRIME SCENE.
Once the trace evidence is collected via vacuuming, taping, or tweezing, take blood samples, remove bullets, dust for fingerprints, and so on.
Processing the crime scene for fingerprints prior to trace evidence collection is not recommended because it can
Inadvertently transfer trace evidence onto the clothing of the technicians,
Move trace evidence, and/or
Contaminate trace evidence with dusting powder.
Evidence Collection
The following are suggestions for collecting evidence from crime scenes such as houses, apartments, and vehicles:
Photograph all evidence prior to removing it.
Remove larger items or debris from carpeting or walk areas prior to other examinations. Consider wearing disposable booties.
Collect large items, such as clothing, and place them in separate paper bags. Keep an accurate evidence log. One person should collect and bag the items while another person labels the bags and records the items in the log.
Do not place all clothing items from a suspect in one paper bag, nor all items from a victim in another bag. Bag each item separately.
Never put suspect items and victim items in contact with one another. The person collecting the suspect’s items should not be the same person that collects the victim’s items. If this must occur, personnel must change their clothing and collect the evidence at a different time to avoid contamination.
Bedding should be carefully handled to avoid loss of hairs and fibers. Each item should be placed in a separate bag.
Floor surfaces should be vacuumed for possible trace evidence. Some crime scene investigators use tape to secure trace evidence; however, tape is generally difficult to work with at the scene and in the laboratory. Smaller surfaces such as chairs and car seats can be taped or vacuumed.
Ensure that carpet, pet hair, and other standards that might have transferred to a suspect or victim are collected.
Always process for fingerprints after collecting trace evidence.
Collect all possible known fiber samples from a vehicle. These may be obtained from the carpet, door panels, headliner, seats, floor mats, and trunk.
The following suggestions pertain to different types of items recovered at the crime scene:
Hats:
Package all hats in separate paper bags. Use care when collecting baseball-style caps with adjustable plastic headbands—the bands are an excellent source for fingerprints.
Shoes:
Shoes are an excellent source of fiber evidence, blood stains, and shoe print comparisons. Shoes worn by a suspect can deposit fibers from a vehicle he or she exited at a crime scene and can also pick up fibers from the scene and then deposit them in another location.
Socks:
Socks worn by a homicide victim can provide invaluable fiber and hair evidence. Many times the victim is transported by vehicle. Contact with the interior surfaces of a vehicle can cause hairs and fibers to collect on the socks. It may be necessary to obtain elimination samples of the carpeting of the victim’s car or residence to avoid the possibility of a coincidental match.
Fingernails:
Use care when scraping or clipping the fingernails of a victim or suspect. DNA on the hands or tools of the medical personnel can contaminate the material and influence the DNA results.
Hairs in the
hands of
the victim:
Hairs found in the hands of the victim usually belong to the victim. Rarely are the hairs similar to the suspect’s known hairs; nevertheless, these must be collected and submitted for analysis.
Pubic and head
hair combings:
Pubic and head hair combings should always be taken in violent crimes. Foreign hairs as well as fibers can be recovered from these samples. If a hat is recovered at the crime scene and a suspect is identified soon, it may be possible to find fibers similar to those in the hat in the suspect’s hair.
Known hair
samples:
Thorough random samples should be taken from the head and pubic regions of a suspect(s) and
victim(s). Twenty-five full-length hairs, pulled and combed from different areas of the head and pubic regions, are generally considered an adequate representation of an individual’s hair characteristics.
Weapons:
Weapons recovered at a crime scene should always be searched for trace evidence before processing for fingerprints.
Doors and
windows:
Doors and windows should be searched for trace evidence if they are possible points of entry or exit.
Explanation:
