Forensic Fiber and Hair Evidence Analysis
Indianapolis-Marion County Forensic Services Agency
See also the instructional videos on "Evidence Collection"
Introduction
Many crimes involve direct physical contact between victim and suspect. Whenever such contact occurs, there is almost always an inadvertent transfer of microscopic evidence. This transfer usually includes hairs and fibers. However, this type of evidence, which can be microscopic in form, may often be overlooked by investigating officers because they are not easily observed. Hairs are readily available for transfer, easily transferred, and resilient. Hair examination may be used for associative and investigative purposes and to provide information for crime scene reconstruction. Even though the most common encountered fibers are white and/or blue polyester, cotton, or blends of these, this type of evidence should be collected and submitted for evaluation. Fibers can be classified as animal (e.g. hair and silk), vegetable (e.g. cotton and linen), mineral (e.g. asbestos), or synthetic (e.g. polyester and nylon), and often identified by sub-classification through laboratory examination.
Types of cases in which fiber and hair may be of value as evidence
- ASSAULT AND HOMICIDE - These types of crimes usually involve personal contact of some sort. Therefore, clothing fibers and hair may be interchanged between victim and suspect; that is, fibers/hairs from victim’s clothing may be found on suspect’s clothing and vice versa. Weapons and fingernail scrapings may also be important sources of fiber evidence. Bindings, such as rope, may also leave distinct fibers if a person was tied up.
- RAPE - The nature of this crime can result in the cross transfer of fibers and hairs between clothing of victim and suspect and such articles as blankets or automobile seat covers. If a victim goes to the hospital for an exam, the hair combings may be good sources of hair and fiber evidence. Weapons and fingernail scrapings may also be sources of fiber evidence.
- BURGLARY - Clothing fibers will frequently be found at the point where the burglar crawled through a window or other opening or climbed over a fence. If no head covering was used, hairs may also be found.
- HIT-AND-RUN - Due to the forceful contact between victim and automobile, clothing fibers and hair can generally be found adhering to the fenders, grill, door handles, or parts of the undercarriage. Fabric impression patterns may also be observed on surfaces with which the fabric came into contact.