For the success of an investigation, trace evidences found at crime scenes are identified and compared. These evidences consist of materials or substances that are generally small in size and can be transferred when physical contact occurs between two individuals, objects or an individual and an object. Hairs and fibers are examples of such evidences. The transfer of hairs and fibers can be critical in associating a suspect to a victim or a crime scene. However, analysis of these evidences requires the understanding of its dynamic nature such as knowing how these can be transferred and the factors that affect the significance of a match in crime scene investigations.
Hairs are composed mainly of the protein keratin and can be defined as slender outgrowths of the skin of mammals. Although it is considered as a benign dead matter, it still contains DNA even though it is not a living organism.
Variability exists in the types of hairs that are found on the body of an animal or human. For humans, hairs found on different parts of our body even have characteristics that can determine their origin. Due to the fact that hairs can be transferred during physical contact, its presence can be associated with a suspect to a crime scene. Comparison of the microscopic characteristics of questioned hairs to known hair samples helps in determining whether a transfer may have occurred.
Types of human hair that can be found at crime scenes:
1. Naturally shed hair – display undamaged, club-shaped roots
2. Forcibly removed hair
a. exhibit stretching and damaged to the root area
b. may have tissue attached
Types of Human Hairs:
1. Head hair – with uniform diameter and often has cut tip
2. Pubic hair – course and wiry and has diameter variation or buckling
3. Facial hair – coarse in appearance and can have a triangular cross section
4. Limb hair – shorter in length, arc-like in shape and often abraded or tapered at the tips
5. Fringe hair – might originate from the neck, sideburns, abdomen, upper leg, and back
6. Other body area hair – underarm, chest, eye, and nose hairs