forensic hair examinations

Question 1

hair as evidence

Answer 1

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

Question 2

can determine

Answer 2

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

Question 3

two methods of analysis

Answer 3

morphological
DNA analysis

Question 4

morphological

Answer 4

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

Question 5

DNA analysis

Answer 5

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

Question 6

goodish evidence

Answer 6

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

Question 7

hair growth

Answer 7

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

Question 8

skin structure

Answer 8

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

Question 9

three phases of hair growth

Answer 9

anlagen
catagen
telogen

Question 10

anagen

Answer 10

active growing phase
follicles produce new cells and pushes them up

Question 11

catagen

Answer 11

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

Question 12

telogen

Answer 12

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

Question 13

human head has

Answer 13

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

Question 14

anatomy of hair

Answer 14

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

Question 15

cuticle

Answer 15

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

Question 16

scale patterns

Answer 16

3 general patterns
coronal
imbricate flattened overlapping
spinous like

Question 17

cortex

Answer 17

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

Question 18

other cortex characteristics

Answer 18

cortical fusi
small bubbles
ovoid nodies
large pigment

Question 19

medulla

Answer 19

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

Question 20

proximal end

Answer 20

root

Question 21

distal end

Answer 21

tip

Question 22

nonhuman hairs

Answer 22

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

Question 23

distinguishing between human and nonhuman

Answer 23

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

Question 24

visualizing scale patterns

Answer 24

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

Question 25

body area determination

Answer 25

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

Question 26

head hair

Answer 26

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

Question 27

pubic

Answer 27

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

Question 28

facial

Answer 28

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

Question 29

chest

Answer 29

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

Question 30

axillary

Answer 30

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

Question 31

limb

Answer 31

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

Question 32

eyebrow and eyelash

Answer 32

diameter is tapering shaft os arc or short tip is pointed

Question 33

buckling

Answer 33

of pubic hair abrupt change in direction twist

Question 34

shouldering

Answer 34

asymmetrical cross section beard hair triangular

Question 35

ancestral estimation

Answer 35

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

Question 36

cross section

Answer 36

African is flattened oval European is oval asian is round

Question 37

african

Answer 37

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

Question 38

european

Answer 38

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

Question 39

asian

Answer 39

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

Question 40

undualtion

Answer 40

moves up and down sin wave

Question 41

damage disease and treatment

Answer 41

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

Question 42

diseases

Answer 42

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

Question 43

hair comparisons

Answer 43

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

Question 44

control samples

Answer 44

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

Question 45

characteristics compared

Answer 45

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

Question 46

DNA

Answer 46

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