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 ID: 738811
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Slide1
HairSlide2
…and more hair.Slide3
Hair as EvidenceCan 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 hairsSlide4
HAIR is useful as forensic evidence because its protein polymers are…Resistant to decomposition and maintains its structure.Slide5
The average human body has about 5 million hairs!Slide6
Some HAIRY facts…The average number of Brown/Black scalp hairs: 100,000! Slide7
On the average, the human scalp has100,000 hair follicles. You are born with as many hair follicles as you are ever going to have!Slide8
Blondes have 120,000Slide9
Redheads have at least80,000Slide10
Average daily # of hairs shed: 50 - 100Slide11
Fastest Growth..Between 15 and 30 years of ageSlide12
Slow Growth..Slide13
Average Scalp hair growth… 0.35 mm/day or about 1 cm/monthSlide14
Hair grows faster … In summerSlide15
Month of greatest hair shed in Northern Temperate zone: NOVEMBERSlide16
Hair Morphology (structure)Slide17
Structure from which hair growsLies below epidermisCan differentiateBetween species
Sticks out of skinSlide18Slide19
The organ that hair grows out ofSlide20
Cross Section of hairThe Hair shaft is made up of….1. The CUTICLE is the outside covering Slide21
a. SCALES cover the cuticleThe cuticle protects the cortexSlide22
In Humans Scale patterns are not useful forensically because the scale patterns in humans are the sameSlide23
In animals, a variety of scale patterns are found
bat
mink
deerSlide24
Scales always point toward the tip of hair(1) mosaicSlide25
(2) pectinateSlide26
(3) imbricateSlide27
(4) petalSlide28
(5) Diamond petalSlide29
(6) chevronSlide30
2. Cortex – gives hair its shape The bulk of each hair’s mass is contained in the cortex. Slide31
The CORTEX… contains the various proteins and bonds which determine the curliness or straightness of the hair. Slide32
a. melaninPigment granules that give hair its colorSlide33
b. Cortical fusiAir spacesUsually found near the rootBut can be foundThroughout the Hair shaftSlide34
3. Medulla – “central canal”-Formed by cells running through hair-Amorphous in appearanceSlide35
Medullary Index = diameter of medulla diameter of hair
The medulla is
approximately.005 mmIn width
This hair is
.
030 mm
in
diameter
The Medullary Index =
.
005
mm
.
030
mm
= 1/6Slide36
Degree of variations in medullasVary from one individual to anotherAnd even between hairs of one person Human hair Medulla index < 1/3 in other animals: ½ or greaterSlide37
a. Types of medullas (Human)continuous
fragmented
absent
Interrupted
or intermittentSlide38
b. Patterns (other animals)Uniserial
multiserialSlide39
(3) Vacuolated Mountain lionSlide40
(4) latticeSlide41
(5) Amorphous – without a clear formSlide42
Hair as Evidence Determine…
1. Human or animal?
In Humans:
Medullary Index
<
1/3
In Other Animals:
Medullary Index
≥ 1/2
Slide43
2. Race (ethnicity)Negroid hairsNegroid or African origin hairs are usually curly with a flattened cross
section and appear to be curly, wavy, or coiled. Slide44
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. Slide45
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. Slide46
3. Origin –from which part of bodyScalp hairs - all about the same diameterBeard hairs - coarse, blunt tips
Pubic hairs - short, curlySlide47
4. Manner in which hair was removedForcibly removed hair will include the root tipSlide48
Follicular Tag contains tissue surrounding hair shaft Contains DNA!!Slide49
5. Treated Haira. rootsSlide50
b. Dye present in cuticle or cortexSlide51
c. Bleached hair Removes color, yellow tintSlide52
6. Drug Testing Hair testing is considered accurate and can go back as far as 90 days Slide53
Hair Comparison
1. Color, straight
vs
wavy
vs curly, etc.Slide54
2. Presence or absence.. of medullaSlide55
3. Pigment Granules In the cortexSlide56
4. Dyed or bleached?Slide57
5. Abnormalities Vitamin deficiency fungus nits (lice)
Or diseasesSlide58
Hair GrowthFunction of the root – nourishment for hair growthSlide59
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 Slide60
Anagen hair rootsSlide61
2. Catagen The root bulb shrinksThe growth rate decreasesLasts 2-3 weeksSlide62
Catagen –TRANSITION stageSlide63
3. TelogenRESTING phase2-6 monthsSlide64
Telogen plase Is also called the SHEDDING phaseSlide65
Hair shed rate 50 – 100 hairs per daySlide66
Each Hair is in Growth phase (Anagen) For 2 – 5 yearsSlide67
% Hair in Growth Phase (Anagen) 85% - 90%