can only compare head hair to head hair or pubic hair to another pubic hair control hairs from...
TRANSCRIPT
Hair as Evidence
Can only compare head hair to head hairor pubic hair to another pubic hair
Control hairs from suspect: 50 full length head hairs minimum of 24 pubic hairs
HAIR is useful as forensic evidence because its protein polymers are…
Resistant to decomposition and maintains its structure.
On the average, the human scalp has
100,000 hair follicles. You are born with as many hair follicles as you are ever going to have!
Structure from which hair grows
Lies below epidermisCan differentiateBetween species
Sticks out of skin
In Humans
Scale patterns are not useful forensically
because the scale patterns in humans are the same
The CORTEX… contains the various proteins and bonds
which determine the curliness or straightness of the hair.
Medullary Index = diameter of medulla diameter of hair
The medulla isapproximately
.005 mmIn width
This hair is .030 mm in
diameter
The Medullary Index = .005 mm .030 mm = 1/6
Degree of variations in medullas
Vary from one individual to another And even between hairs of one person
Human hair Medulla index < 1/3
in other animals: ½ or greater
a. Types of medullas (Human)
continuousfragmented
absent
Interrupted or
intermittent
Hair as EvidenceDetermine…
1. Human or animal? In Humans: Medullary Index < 1/3 In Other Animals: Medullary Index ≥ 1/2
2. Race (ethnicity)
Negroid hairs
Negroid or African origin hairs are usually curly with a flattened cross section and appear to be curly, wavy, or coiled.
Caucasian hairs
Caucasoid or Caucasian origin hairs are normally fine to medium coarseness, oval cross-section, straight or wavy in appearance, and colors range from blonde to brown to black.
Mongoloid or Asian hairs
Mongoloid or Asian origin hairs are normally coarse, straight, with a wider diameter than hairs of the Caucasoid and Negroid hairs. The outer layer of the hair is usually much thicker than that of the other racial groups.
3. Origin –from which part of body
a. Scalp hairs - all about the same diameter
b. Beard hairs - coarse, blunt tips
c. Pubic hairs - short, curly
Hair Comparison
1. Color, straight vs wavy vs curly, etc.
2. Presence or absence..
of medulla
4. Dyed or bleached?
5. Abnormalities Vitamin deficiency fungus
nits (lice)
Or diseases
A. TERMINOLOGY Phases of growth
1. anagen - the root
is attached to the follicle GROWTH PHASE lasts 2-6 yrs 90%of hair is in anagen
Each Hair is in Growth phase (Anagen)
For 2 – 5 years