DNA Evidence ■ Root: nuclear DNA ■ Shaft: mitochondrial DNA (mtDNA)
Growth Stages of the Hair: ■ Anagen Stage: The active growth phase of the hair follicle. ■ Catagen Stage: The transition period between growth and rest. Hair continues to grow, but at a decreasing rate. The root bulb looks elongated from being pushed out of the follicle. ■ Telogen: The rest period for the follicle. The current hair is shed and no new growth takes place for a period of time.
Hair as Forensic Evidence
Hair Collection ■ Collected from crime scene by plucking, shaking and scraping surfaces ■ Use tape over small surfaces ■ Vacuum large surfaces ■ Initial analysis performed under compound microscope ■ Collect 50 hairs from suspect for comparison. Not all hairs are the same
Testing For Chemicals ■ Neutron activation analysis (NAA) – identify 14 different elements in hair ■ Antimony, argon, bromine, copper, gold, manganese, silver, sodium, zinc ■ Hair grows about 1.3 cm per month – calculate timeline for exposure to toxins or poison