Unit 9- Hair and Fibers

Question 1

Fibers are considered to be ________ because they are generally _______

Answer 1

class evidence, mass produce

Question 2

Fibers are used to

Answer 2

create a link between crime scenes and subjects.

Question 3

Fibers can originate from many different sources:

Answer 3

carpeting, clothing, linens, furniture, insulation, rope/ligature, tape, paper

Question 4

Two General Types of Fibers:

Answer 4

1) Natural
derived from animal hairs or plants
2) Synthetic
man-made

Question 5

Natural Fibers: Animal Hairs

Answer 5

Sheep (wool); most common
Goat (mohair and cashmere)
Camel (wool)
Llama
Alpaca (wool)
Fur βibers from mink, rabbit, beaver, etc.
Silk (βiber from the cocoon of the silkworm)

Question 6

Natural Fibers: Plant Fibers

Answer 6

cotton most common; ribbon-like shape with irregular twists
βlax (linen)
ramie
sisal often used in linen rugs
jute often used in ropes
hemp common name for cannabis for industrial/non-drug use;
typically used for rope or sack
kapok fiber from kapok tree seed pods; used in pillows and
mattress stuffing
coir coconut husks; used in carpet and rugs

Question 7

Acrylics

Answer 7

> wool-like; soft and warm
quick drying and resistant to moth

Question 8

Rayon

Answer 8

> cellulose-derived regenerated thin βiber

Question 9

Acetates

Answer 9

> cellulose-based wrinkle resistant βiber

Question 10

Nylon

Answer 10

> also common; elastic and strong
lustrous and silk-like when stretched
βirst created by DuPont in 1935

Question 11

Kevlar

Answer 11

> light, but strong synthetic βiber developed by DuPont in 1965
heat resistant
typically used for bullet-proof vests, military applications, racing
tires, etc.

Question 12

Nomex

Answer 12

> a variation of Kevlar
βire resistant
used by firemen and disaster response teams

Question 13

Fiber

Answer 13

> a fine, slender piece of thread or filament

Question 14

Yarn

Answer 14

> a twisted aggregate of fibers

Question 15

Textile

Answer 15

> woven fibers; fabric

Question 16

Weaving

Answer 16

Lengthwise threads (warps) are woven by crosswise threads (wefts) in a repeated pattern.

Question 17

Plain

Answer 17

> firm; tends to wrinkle

Question 18

Basket

Answer 18

> not very durable
shrinks when washed

Question 19

Satin

Answer 19

> not durable
shiny surface

Question 20

Twill

Answer 20

very strong, dense and compact, but soft

Question 21

Leno

Answer 21

> open weave
easily distorted

Question 22

Microscopic Comparisons

Answer 22

> color
diameter
surface markings
delustering agent (TiO2 added to reduce shine)

Question 23

Polarized Light Microscopy

Answer 23

determines birefringence using polarized light
(difference between two refractive indices)

Question 24

Fourier Transform Infrared Spectroscopy (FTIR)

Answer 24

analysis of chemical composition based on their ability to absorb light at different wavelengths

Question 25

UV/Visible Microspectrophotometry

Answer 25

distinguishes slight/subtle color differences based on absorption of light at different wavelengths in the ultraviolet and visible range

Question 26

Significance of Fiber Evidence

Answer 26

The Questioned fiber could have originated from the known sample. The Questioned fiber did not originate from the source represented by the known sample.

Question 27

The number of fibers is _______ to the likelihood of actual contact (i.e., the greater the number of fibers, the more likely that contact actually occurred).

Answer 27

directly proportional

Question 28

Hair ƒ‹”

Answer 28

a slender threadlike outgrowth from the follicles of the skin of mammals

Question 29

Keratin ‹•ˆ‘—†ƒŽŽ‘˜‡”‘—”„‘†›

Answer 29

a protein that makes up most of the hair shaft

Question 30

Pigment (gives hair its color)

Answer 30

- melanin - pheomelanin (redheads only)

Question 31

Cortex ‘”–‡š

Answer 31

the main body of a hair (wooden portion of a pencil)

Question 32

Medulla

Answer 32

the central cells of the cortex (the lead of a pencil); not always present

Question 33

cuticle

Answer 33

a layer of scales covering the hair shaft (a layer of yellow paint on a pencil)

Question 34

proximal end

Answer 34

root

Question 35

distal end

Answer 35

tip

Question 36

ovoid bodies

Answer 36

- spheric to oval structure - mostly found in cattle and dog hairs, but also in some human hairs Ž•‘‹•‘‡ Š—ƒŠƒ‹”•

Question 37

cortical fusi

Answer 37

elongated spindle-shaped air spaces in the cortex

Question 38

anagen phase

Answer 38

- active growth stage -ribbon like tip - found with follicular tag

Question 39

catagen phase

Answer 39

intermediate stage of growth

Question 40

telogen phase

Answer 40

- resting stage - has a bulb like shape - often found with very little pigment - often found with abundance of cortical fusi

Question 41

hairs that are forcibly removed often end up with a ____ attached to the proximal end

Answer 41

follicular tag

Question 42

Postmortem root band (dead man's. root)

Answer 42

a dark band that may appear near the root of the hair originating from a decomposing body

Question 43

pigments

Answer 43

human: constant color and pigmentation throughout the hair shaft animal: often seen with radical color changes

Question 44

medulla

Answer 44

Human: thin and amorphous Animal: wide, regular, well-defined, repeated patterns

Question 45

scale structures

Answer 45

Human: - overlapping imbricate scales - flattened with narrow margins Animal: - imbricate scales - crown-shaped coronal scales - petal-shaped spinous scales

Question 46

caucasian

Answer 46

- moderate shaft diameter with very little variation - light to moderate pigment density with fairly even distribution - oval- shaped cross section

Question 47

mongoloid

Answer 47

- coarse shaft diameter - streaky pigments with heavy density - thick cuticle - round cross-section

Question 48

negroid

Answer 48

- fine to moderate shaft diameter - considerable variation throughout the hair shaft with prominent twists curls - heavy pigment density with aggregate pigment clumpings - flat cross-section

Question 49

head hairs

Answer 49

-much longer than other hair types -soft - have artificial treatment

Question 50

pubic hairs

Answer 50

- often coarse in diameter with wide variations - prominent "buckling"

Question 51

limb hairs (arm or leg)

Answer 51

- fine diameter with little variation - arc-like gross appearance - usually tapered or abraded

Question 52

facial hairs (beard/mustache)

Answer 52

-very course diameter with irregular or triangular cross-section - very broad and continuous medulla - often with double medulla - stiff texture

Question 53

chest hairs

Answer 53

- moderate and variable shaft diameter - tip often dark in color - long and fine - arc-like gross appearance - granular medulla - stiff

Question 54

axillary hairs

Answer 54

- less buckling. - medulla similar to limb hairs - fine tip

Question 55

eyebrow and eyelash

Answer 55

stubby and sabber like appearance

Question 56

fur hair vs guard hair in animals

Answer 56

fur: fine diameter, designed for insulation guard: coarse diameter, designed for protection

Question 57

pili annulati

Answer 57

ringed or banded hairs

Question 58

trichorrhexis nodosa

Answer 58

conspicuous nodes due to immuneodefiency or small bowel disorder

Question 59

information provided by hair examination

Answer 59

- human or animal - race - where in the body

Question 60

information not provided by hair examanation

Answer 60

age and gender

Question 61

hair may be used to distinguish identical twins who

Answer 61

cannot be distinguised based on their DNA because of environmental effects

Question 62

polyester

Answer 62

- wrinkle resistance. - cotton