FRSC 1011H Lecture Notes - Lecture 7: Phase Transition, Pubic Hair, Melanin
7 May 2018
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Trace Evidence
Trace Evidence in the lab
● Most common physical evidence that undergoes standard lab analysis using
morphological observation
○ Hair
○ Paints
○ Glass
○ Fibers
○ Soil
Hair
● When properly collected and submitted to the lab accompanied by an adequate
number of standard/ reference samples, hair can provide strong corroborative
evidence for placing an individual at a crime scene.
Hair Root
● When pulled from the head, some translucent tissue surrounding the hair’s shaft
near the root may be found. This is called a follicular tag
● By using DNA analysis on the follicular tag, the hair may be individualized
Hair Growth
● Anagen Phase
○ The initial phase of growth in which the hair follicle is actively producing
hair
○ The root bulb would appear flame shaped
● Catagen Phase
○ Transition phase of growth
○ Root appears elongated
● Telogen Phase
○ Final growth phase in which the hair falls out of the skin
○ Root takes on club-shaped appearance
Factors to Consider
● Is the hair bleached or dyed?
○ Dyed color is present in the cuticle as well as the cortex
○ Bleach hair removes all melanin from the cortex leaving it a yellowish color
Document Summary
Most common physical evidence that undergoes standard lab analysis using morphological observation. When properly collected and submitted to the lab accompanied by an adequate number of standard/ reference samples, hair can provide strong corroborative evidence for placing an individual at a crime scene. When pulled from the head, some translucent tissue surrounding the hair"s shaft near the root may be found. By using dna analysis on the follicular tag, the hair may be individualized. The initial phase of growth in which the hair follicle is actively producing hair. The root bulb would appear flame shaped. Final growth phase in which the hair falls out of the skin. Dyed color is present in the cuticle as well as the cortex. Bleach hair removes all melanin from the cortex leaving it a yellowish color. The collection of 50 full length hairs from all areas of the scalp will normally ensure a representative sampling of head hair.
