Hair and more hair Hair as Evidence Can

Hair

…and more hair.

Hair as Evidence Can only compare head hair to head hair or 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.

� The average human body has about 5 million hairs!

Some HAIRY facts… The average number of Brown/Black scalp hairs: 100, 000!

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!

Blondes have 120, 000

Redheads have at least 80, 000

Average daily # of hairs shed: 50 - 100

Fastest Growth. . Between 15 and 30 years of age

Slow Growth. .

Average Scalp hair growth… 0. 35 mm/day or about 1 cm/month

Hair grows faster … In summer

Month of greatest hair shed in Northern Temperate zone: NOVEMBER

Hair Morphology (structure)

Sticks out of skin Structure from which hair grows Lies below epidermis Can differentiate Between species

The organ that hair grows out of

Cross Section of hair The Hair shaft is made up of…. 1. The CUTICLE is the outside covering

a. SCALES cover the cuticle The cuticle protects the cortex

In Humans Scale patterns are not useful forensically because the scale patterns in humans are the same

In animals, a variety of scale patterns are found deer bat mink

Scales always point toward the tip of hair (1) mosaic

(2) pectinate

(3) imbricate

(4) petal

(5) Diamond petal

(6) chevron

2. Cortex – gives hair its shape The bulk of each hair’s mass is contained in the cortex.

The CORTEX… contains the various proteins and bonds which determine the curliness or straightness of the hair.

a. melanin � Pigment granules that give hair its color

b. Cortical fusi Air spaces Usually found near the root But can be found Throughout the Hair shaft

3. Medulla – “central canal” -Formed by cells running through hair -Amorphous in appearance

Medullary Index = diameter of medulla diameter of hair This hair is. 030 mm in diameter The medulla is approximately. 005 mm In width 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) Interrupted or intermittent fragmented absent continuous

b. Patterns (other animals) (1) Uniserial (2) multiserial

(3) Vacuolated Mountain lion

(4) lattice

(5) Amorphous – without a clear form

Hair as Evidence Determine… 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 Scalp hairs - all about the same diameter b. Beard hairs - coarse, blunt tips a. c. Pubic hairs - short, curly

4. Manner in which hair was removed Forcibly removed hair will include the root tip

Follicular Tag contains tissue surrounding hair shaft Contains DNA!!

5. Treated Hair a. roots

b. Dye present in cuticle or cortex

c. Bleached hair Removes color, yellow tint

6. Drug Testing Hair testing is considered accurate and can go back as far as 90 days

Hair Comparison 1. Color, straight vs wavy vs curly, etc.

2. Presence or absence. . of medulla

3. Pigment Granules In the cortex

4. Dyed or bleached?

5. Abnormalities Vitamin deficiency fungus nits (lice) Or diseases

Hair Growth Function of the root – nourishment for hair growth

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

Anagen hair roots

2. Catagen � The root bulb shrinks � The growth rate decreases � Lasts 2 -3 weeks

Catagen –TRANSITION stage

3. Telogen �RESTING phase � 2 -6 months

Telogen plase Is also called the SHEDDING phase

Hair shed rate 50 – 100 hairs per day

Each Hair is in Growth phase (Anagen) For 2 – 5 years

% Hair in Growth Phase (Anagen) 85% - 90%