Hair with an anagen root is a good source of nuclear DNA
The average person typically sheds about 100 hairs per day. These hairs may be of evidentiary value to show contact between two people or a person to a place. Items such as clothing, bedding or hats can be examined in the laboratory for the presence of hairs. With an adequate hair standard of about 50 pulled head hairs or 25 pulled pubic hairs, a question hair may be microscopically compared to a standard collection to determine if the question hair could have come from the individual under investigation. Hairs can additionally be screened for eligibility for nuclear DNA analysis.
Microscopic hair comparisons cannot identify a hair as coming from one individual to the exclusion of everyone else. DNA testing can strengthen any possible microscopic association of the hairs. Hair examinations are performed using microscopy.
Hair with a catagen root may yield nuclear DNA
Hair with a telogen root is naturally shed and is not a good source of nuclear DNA
Photomicrograph of human hair root with fluorescent dye revealing nuclei for DNA testing