TRACE EVIDENCE: HAIR
Anatomy of a Hair
 Cortex
Largest portion of the shaft
Contains hair pigment
 Cuticle
Layer of cells that cover the surface of the shaft
Look like fish scales and have distinct patterns
 Coronal (crownlike) – rarely found in humans, common in
rodents
 Spinous (petallike) – triangular in shape, not found in
humans, common in cats
 Imbricate (flattened) – found in humans and many other
animals
 Medulla
Central core of the hair
Medullary index is the width of the hair. Animals index is
greater than .5, humans .3
Criminologist
At the crime scene you can collect hair by
Filter paper on a vacuum cleaner
Tape lifts
Collecting actual samples from victims or
suspects (generally collect 50 + hairs)
Criminlogist
 Compare unknown sample of hair to known
samples using a comparison microscope
Color and width
Distribution pattern of the medulla
Color and distribution pattern of pigment in the cortex
Cuticle pattern
Appearance of root tip (damaged could represent
struggle)
Tip appearance
 If root or bulb is found then DNA can be
extracted
Criminologist
Chemical testing
Chemicals absorbed by skin can be detected in
hair shaft
Sectional analysis can establish timeline for
exposure to toxins
Neutron Activation Analysis (NAA) read John
Vollman case from Forensics for Dummies
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