Forensic Hair Analysis
Basic Features of Hair
❑ One of the most frequently found pieces of
evidence at the scene of a violent crime.
❑ From hair, you can determine:
❑
❑
❑
❑
❑
❑
❑
If hair is human or animal
Ancestry
Whether the hair was forcibly removed
Origin from the body
If hair has been treated with chemicals
If drugs have been ingested
Identification through DNA analysis
Biology of Hair
❑ Hair is composed of the protein keratin
(which is also the main component of
finger and toe nails)
❑ Hair is produced from a
structure called the hair follicle.
❑ Follicular tag – tissue
surrounding the root; rich in
DNA
COOL FACT: No new follicles are produced after birth.
Hair Structure
❑ Three basic parts
❑ Cuticle - outer layer;
made of overlapping
dead keratin cells (scales)
❑ Cortex - the middle layer
that contains pigment
❑ Medulla - the core of the
hair; may be absent
Hair Structure
Human Hair Structure
❑ Cuticle
❑ Three
basic cuticle patterns
❑ Humans
pattern
will always be an imbricate
Human Hair Structure
❑ Medulla
❑ Human
medullas are considered amorphous
❑ Width
is less than 1/3 the overall diameter of the shaft
❑ Three
basic medullary patterns
Absent
Continuous
Fragmented/Interrupted
Human Hair Structure
Human Hair Shape
Straight Hair
Curly/Wavy Hair
Kinky Hair
Human Hair Shape
❑ When
human hair is viewed in cross-section, there is a
correlation between hair shape and ancestry
❑ Round/Circular
❑ Oval
❑ Flat
(Asian)
(European)
(African)
Human Hair Growth
❑ Anagen
Phase
❑ Catagen
❑
Hair is actively growing
❑ Follicle
❑
Lasts up to 5 years
❑ Hair
❑
About 85% of hair is in this
phase at any one time
Phase
shrinks
is cut from blood
supply and growth stops
❑ Lasts
2-3 weeks
❑ Telogen
❑ Hair
rest
is completely at
❑ Lasts
about 2-6 months
❑ Results
hair
in shedding of
If a hair is forcibly removed…
Anagen Phase
Forcibly removed with
follicular tag; “flame shaped”
Catogen Phase
Forcibly removed; root is
stretched/damaged;
“elongated shape”
Telogen Phase
Naturally shed; Root is
undamaged;
“club shaped”
Hairs From Different Parts of the Body
❑6
Main Types of Hair
❑ Head
Buckling
hair
❑ Eyebrows/eyelashes
❑ Beard/mustache
❑ Underarm
❑ Body
❑ Pubic
hair
Double medulla
hair
hair
Frayed end
STATIONS
1.
Identify human medulla patterns
2.
Identify stages of hair growth
3.
Create a cuticle cast of your hair
4.
Identify ancestry
5.
Hair and DNA