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4090 final > forensic hair examinations > Flashcards

forensic hair examinations Flashcards

1
Q

hair as evidence

A

frequently found item
can associate suspect to victim, weapon, crime scene

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2
Q

can determine

A

source is human or animal
race
forcibly removed
treated with chemicals
drugs were ingested
source

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3
Q

two methods of analysis

A

morphological
DNA analysis

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4
Q

morphological

A

trace analysis
what does it look like macroscopically and microscopically
determine if it is hair, human hair
which hair is best for DNA analysis
done first, non-destructive

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5
Q

DNA analysis

A

done last
destructive
hair will be consumed
hair with root has possible nuclear DNA
hair without root has mitochondrial DNA

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6
Q

goodish evidence

A

abundant
average person has >100,000 hair follicles on head
humans and animals are useful
easily transferable
average person sheds 100 hairs a day
sturdy and durable
can survive for many years
mummies dating back 2000 years
mtDNA is not as fragile as nuclear DNA
diverse carries a lot of info
human/non-huuman
different body areas
DNA
easy and cost-effective to examine

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7
Q

hair growth

A

only common to mammals
fibrous growths that originate from skin
made of keratin
tough protein based material
goes through keratinization
hardening process

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8
Q

skin structure

A

follicle structure within which the hair grows
only place where hair is alive
root vs shaft
sebaceous sweat glands
arrestor pili muscle makes hair raise

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9
Q

three phases of hair growth

A

anlagen
catagen
telogen

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10
Q

anagen

A

active growing phase
follicles produce new cells and pushes them up

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11
Q

catagen

A

transitional phase
follicle begins to stop producing cells, root condenses to root bulb

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12
Q

telogen

A

resting phase
follicle has ceased cell production
root no longer has a tissue connection to follicle
easily shed/ combed out
once a telogen hair is shed, process begins over

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13
Q

human head has

A

80-90% anagen
2% catagen
10-18% telogen

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14
Q

anatomy of hair

A

macroscopically
root, shaft, tip
microscopically (within the shaft)
cuticle, cortex medulla

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15
Q

cuticle

A

outer covering made up of scales
protective covering
differ between species of animal
used to distinguish human hair from nonhuman hair

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16
Q

scale patterns

A

3 general patterns
coronal
imbricate flattened overlapping
spinous like

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17
Q

cortex

A

bulk of hair
gives hair its shape
pigmentation
melanin- pigment granules that give color

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18
Q

other cortex characteristics

A

cortical fusi
small bubbles
ovoid nodies
large pigment

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19
Q

medulla

A

hairs core
types
fragmented, medullary disruptions
continuous, along entire length
absent, may be missing or can’t see it

20
Q

proximal end

A

root

21
Q

distal end

A

tip

22
Q

nonhuman hairs

A

3 types
guard hairs
large stiff hairs that make up the outer coat
these should be used for microscopic comparison
fur hairs
thinner soft hairs that fill in for warmth an bulk
vibrissa
whiskers

23
Q

distinguishing between human and nonhuman

A

cuticle scales
human is flattened, nonhuman has pattern variation
medulla
human is amorphous, nonhuman is structured
color
human is relatively consistent, nonhuman varies/banding
cortex
human is most of the shaft, nonhuman is less than the width of the medulla

24
Q

visualizing scale patterns

A

scanning electron microscope
scale cast
clear nail polish on microscope slide
lay hair in wet polish
when almost dry, peel hair out
examine under microscope

25
Q

body area determination

A

humans have a wide variety
head pubic are both suitable for microscopic comparison
facial chest axillary eyelash/eyebrow, limb
physical characteristics of the hair may help in determining what part of the body the hair is from

26
Q

head hair

A

even diameter
shaft is straight or curly, some waviness, may be very long
tip is usually cut

27
Q

pubic

A

diameter varies
buckling in shaft sometimes extreme waviness or curl
tip usually pointed may be razor cut

28
Q

facial

A

diameter is wide and even
shaft is triangular in cross section, some shouldering
tip is usually cut may be scissors or razor

29
Q

chest

A

diameter is even to some variation
shaft is wavy or curly some more straight
tip is usually pointed

30
Q

axillary

A

diameter is even to some variation
shaft is less wavy/curly than chest
tip is usually pointed, may be colorless

31
Q

limb

A

diameter is fine, tapering
shaft has slight arc
tip is usually pointed

32
Q

eyebrow and eyelash

A

diameter is tapering
shaft os arc or short
tip is pointed

33
Q

buckling

A

of pubic hair
abrupt change in direction
twist

34
Q

shouldering

A

asymmetrical cross section
beard hair triangular

35
Q

ancestral estimation

A

determination of race from hair characteristics
need a representative sample to account for variation ~ 50 hairs
can be very challenging cuz mixed races and variation
asian hair is heavily pigmented and thicker
African hair often has undulation, curls

36
Q

cross section

A

African is flattened oval
European is oval
asian is round

37
Q

african

A

diameter 60-90
cross section flat
pigment dist dense, clumped
cuticle is thin
undulation is prevalent

38
Q

european

A

diameter 70-100
cross section is oval
pigment is even dist
cuticle is medium
undulation is uncommon

39
Q

asian

A

diam is 90-120
cross section is round
pigment is dense to very dense
cuticle is thick
undulation is never

40
Q

undualtion

A

moves up and down
sin wave

41
Q

damage disease and treatment

A

tips of hair can provide good info about treatment
scissor cut is straight
razor cut is angled
burned hair expanded or bubbled
bleaching or dyeing abrupt color change due to hair growth

42
Q

diseases

A

pili annulati
colored bands like zebra stripes
monilethrix
varying diameter, patchy hair loss
pili torti
twisting of hair, fractures in cuticle/cortex

43
Q

hair comparisons

A

questioned hairs must be accompanied by adequate control samples from victim for exclusion, from possible suspects, from others who may babe deposited hair at the scene

44
Q

control samples

A

head/scalp 50 full length hairs
pubic 25 full length
need to collect in same time frame as crime
hair can change, dye

45
Q

characteristics compared

A

color/treatment , not dependable
length/ diameter
medulla structure
condition/damage
disease
very subjective
natural variation
usually report as similar or consistent

46
Q

DNA

A

root contains DNA
if hair has been forcibly removed some follicular tissue may be attached, nuclear DNA
hair shaft has abundance of mitochondrial DNA

4090 final (6 decks)

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