Hair - Analysts can tell investigators if individual hairs are human or animal, and in the case of human hair, where on the body the sample originated. Samples can be tested to determine the color, shape and chemical composition of the hair, and often the race of the source individual. The presence of toxins, dyes and hair treatments are noted. This information can assist investigators in including or excluding particular individuals as the source of the hair. If the hair still has a follicle (root) attached, DNA testing may be used to identify an individual; otherwise, hair comparison is typically used only to exclude.

Fiber - Fibers are threadlike elements from fabric or other materials such as carpet. Most are easily identifiable under a microscope. Fibers fall into three classifications: natural (animal or plant fibers like wool, cotton or silk), synthetic (completely manmade products including polyester and nylon) and manufactured (containing natural materials that are reorganized to create fibers such as rayon).

Fibers are useful in crime scene investigation because their origins can be identified. A carpet fiber on a person’s shoe can indicate the individual’s presence at a crime scene. However, fibers are very mobile and can become airborne, get brushed off or fall from clothing. This mobility makes timely collection crucial to prevent loss of material or cross-contamination.

Collection: Fibers cling to other fibers and hair, but may be easily brushed off. When approaching a scene, investigators will attempt to pinpoint the most probable locations for deposited fibers. For example, the carpeting under and surrounding a victim’s body, clothing from the victim or a suspected weapon are likely places to find fibers.