Ch. 3
Hair
Napoleon Hair (watch beginning)
Neutron activation analysis (old)- 18 min
Napoleon Poisoning Claims Debunked
Forensic Analysis of Hair
Trace evidence- hair and fiber
Hair Evidence
Class evidence
1st job: determine if animal or human
Composed of protein (keratin), an appendage of
the skin that grows out of hair follicle
Each species possesses hair w/ characteristics
length, color, shape, root appearance & internal
features
Types of hair recovered & condition & number of
hairs collected all impact their value as evidence
Morphology
Study of the structure or form of hair
Function of Hair
Regulate body temp
Decrease friction
Protect against sunlight
Sense organ
Camoflauge
The Structure of Hair
The Structure of Hair
The Structure of Hair
Phases (development stages)
Anagen
Cyclical growth
Initial growth period where follicle is
actively producing hair (materials are
deposited in cells)
May last 3-6 years, 80-90 % of hair is this
phase
Follicular tag- root is attached to follicle for
growth, when hair is yanked out root is still
attached- can use tag for DNA
Catagen
Transition period
Occurs between anagen & telogen phases
2% in this phase
Roots are elongated
Telogen
Resting phase
10-18% of hair
Most commonly found piece of evidence
Last about 100 days, easily dislodged
Root is club shaped
Final growth phase in which hair sheds
Parts of Hair
Hair is an appendage of the skin that grows
out of an organ known as the hair follicle
Hair follicle: origin of growth of the root,
shaft and tip

club shaped structure in skin w/ network of
blood vessels called papilla that supply
nutrients
Shaft: composed of protein keratin, consists
of 3 layers
Cuticle
Allows hair to be resistant to chemicals &
allows hair to retain structural features over
a long time
Formed by overlapping scale (hardened
cells)
Scales on animals look like roof shingles
Scales can be: coronal, spinous, or
imbricate
Study by making casts (embedded in nail
polish)
Cortex
Main body of hair
Contained w/ in the protective cuticle
Made of spindle-shaped cortical cells
aligned in the shaft
Pigment granules found in cortex (major
use in evidence- get diff. shapes, color,
distribution)
Can look at cortex if you prepare slide w/
liquid that has same index of refrac. as hair
Medulla
Collection of cells having the appearance of a
central canal running through hair
Varies among individuals
Classified as continuous, interrupted, fragment,
absent
Medullary index (M.I.) = diameter of medulla
diameter of shaft
Casey anthony -hair
Other types of human hair
-used to corroborate other evidence
-make connections
Pubic
Need 25 hairs, routinely compared (head
hair- normally 50)
Not subject to change (sample can be taken
1 year after crime- can still be compared)
Course and wiry, buckling can be present
Facial
Not meaningful, establish contact
Coarse, triangular cross section
Wide medulla, razor cut tip
Limb Hairs
Not meaningful
Short, arc like
Medulla – trace to discontinuous
Fringe hairs
Neck, side burns, abdomen, upper leg, back
Other body hair
Underarm, chest, eye, nose
Not routinely compared
Animal Hair
Used to link a suspect or location
Get transfer (from animal or secondary source)
Animals don’t possess enough indvl.
microscopic characteristics to be associated w/
1 particular animal
Can determine type of animal or breed
Animal hairs vary- in color & length from
different parts of the body
Collect full length hairs
Some hairs found may be cut  fur coat,
rug, etc
Animals vs. Humans
Animal
MI  ½ or greater
Medulla= continuous
or interupted
Shape = patterned


Cat=pearl
Deer = spheres
Human
MI  1/3 or less
Medulla= fragmented
or absent
Shape = cylindrical
Age and Sex
Age
Can’t be determined definitively by microscope
 But hairs in infants  finer, less distinctive
 Older hair  finer, more variable in diameter

Sex
Can do DNA w/ follicular tag (rare)
 Can also stain the sex chromatin in cells (Barr
body or y-body)
 Treated (perm,color) more frequent in females

Barr Body
Y-Body
Racial Determination
Caucasoid (European)
Fine to medium coarseness
 Straight or wavy
 Blonde to brown/black in color
 Shafts – round to oval in cross section
 Have medium sized, evenly distributed pigment
granules
 Color- blonde, red, brown or black

Mongoloid (Asian)
Coarse, straight, circular cross section
 Wider diameter
 Cuticle thicker
 Medulla continuous & wide
 Pigment granules are larger than caucasoid,
densely distributed
 Can have reddish appearance

Negroid (African)
Curly, kinky
 Flattened cross section
 Pigment granules are larger than other groupsin clumps
 Can be buckled (twisted shaft) & shaft is
frequently split

Identification and comparison of
hair
Hair is class evidence
Identification involves:

Scale structure, medullary index, medullary
shape
Compare:

Color, length, diameter, medullary charac.,
cortical cells, artificial pigmentation (dyed or
pigmentation – 1cm/month growth)
Forensic exam:

Addresses body area, racial origin, mechanism
of removal, possibly age or sex
Analysis Techniques
Microscopy:
Compound
 Comparison (most common)
 Fluorescence
 Electron

Neutron Activation Analysis- method of
analysis that determines the composition of
elements
Buckled hair
Cut tip
Burnt hair
Razor
cut
Split end
Post mortem
root band
Human hair
Orangutan
Bat hair- coronal pattern
Mink hair- spinious
Rabbit- ladder
medulla
Dyed hair
Hair w/ lice
egg
Pubic hair
Limb hair
Beard hair
FBI Hair Website
fbi video (old)