Hair Analysis
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It’s Everywhere!!!
When is it used?
Forensic hair examinations and
comparisons are often used as
important investigative and associative
information
 Individual Evidence: evidence which
can only be linked to one person
 Class Evidence: evidence that can be
linked to a group of people
 Hair evidence is class evidence

Why is hair evidence
used?
Hair is:
a.
readily available
b.
easily transferred
c.
difficult to destroy

What can be determined
from hair?
If the source is animal or human
 Race (sometimes)
 Where on the body the hair came from
 Whether the hair was forcibly removed
 If the hair has been treated with chemicals
 If drugs have been taken into the body

Hair of Infant
Hair of Adult Female
Hair Adult Male
Arm Hair Adult Male
Beard Hair
Parts of the Hair
Cuticle: outside covering of the hair;
made of overlapping scales
 Cortex: Inner layer made of keratin
and imbedded with pigment (color)
 Medulla: inside layer running down
the center of the cortex

Cuticle Scale Patterns

Scales differ between species of animals and
are named based on their appearance.
Steps to Visualizing
Human Scales
1. paint clear fingernail polish on a glass
slide
2. when the polish begins to dry, place a
hair on the polish
3.when almost dry, lift off the hair and
observe the scale imprints
Types and Patterns of
Medulla
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Intermittent or interrupted
Fragmented
Continuous
Stacked
Absent—not present
Human Medulla
Human medulla may be
continuous, fragmented or
absent

Medullary Index
Determined by measuring the diameter of the
medulla and dividing it by the diameter of the
hair.

Medullary Index for human hair is generally
less than 1/3.

For animal hair, it is usually greater than 1/2.
What gives hair its shape?

Hair can be straight, curly or kinky
depending on the cross-section of the hair
Hair Growth
 Terminology
 Anagen—hair that is actively growing;
lasting up to 5 years
 Catagen—hair is not growing; a resting
phase
 Telogen—hair that is dying and ready to fall
out; lasting two to six months
 Grows about 0.5 mm per day or 1 centimeter
per month; approximately one half inch per
month
Comparing Hairs
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Color
Length
Diameter
Distribution, shape
and color intensity of
pigment granules
 Dyed hair has
color in cuticle and
cortex
 Bleaching removes
pigment and gives
a yellow tint
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Scale types
Presence or
absence of
medulla
Medullary
type
Medullary
pattern
Medullary
index
Examples of Hair Basics
Cut with
Scissors
Cut with
Razor
More Hair Basics
Naturally Shed, Buckling and Forcibly
Pulled
Pulled & Broken
Naturally
Shed
Forcibly pulled with tissue
attached
Other Hair Damage
Fire Damage
Burned
Buckling
Collecting Hair
Questioned hairs must be accompanied by an
adequate number of control samples
a. From victim
b. From possible suspects
c.
From others who may have deposited hair at
the scene

Control Sample: a group of known materials
used for comparison
DNA from Hair

Nuclear DNA- if tissue is still attached from
being forcibly removed-traces to individual

Mitochondrial DNA- if not forcibly removedshows only DNA inherited from the mothertraces to maternal line
Hair Toxicology
Toxicology: the study of the nature, effects and
detection of poisons and the treatment of
poisoning
 Advantages of Hair Toxicology:
a.
Easy to collect and store
b. Externally available
c.
Can provide information on the individual’s
history of drug use or poisoning

Collections from all areas of the body can give an
accurate timeline of exposure or use
Case Study: Napoleon

Napoleon died in exile in 1821.
By analyzing his hair, some
investigators suggest he was
poisoned by the deliberate
administration of arsenic;
others suggest that it was
vapors from the dyes in the
wallpaper that did him in.
Case Study: Edgar Allan
Poe
On October 3, 1849, Poe was found

delirious on the streets of Baltimore,
Maryland, "in great distress, and ...
in need of immediate assistance",
according to the man who found
him, Joseph W. Walker.[He was taken
to the Washington College Hospital,
where he died at 5 a.m. on Sunday,
October 7. Poe was never coherent
enough to explain how he came to
be in this condition. Some believe he
was poisoned as a part of a political
election corruption scheme
More About Hair
For additional information about hair
and other trace evidence, check out
Court TV’s Crime Library at:
www.crimelibrary.com/criminal_mind/f
orensics/trace/1.html