Forensics Hair and Fibers

Human hair is on the most

frequently found pieces of evidence at crime scenes

hair can provide a link between

a criminal and a crime

from hair one can determine

human or animal, race (sometimes), origin or of location on the body, whether it was forcibly removed,

if it was forcibly removed, if drugs were ingested

Alfred Swaine Taylor and Thomas stevenson

covered hair in a forensic science textbook; first to do so

Victor Balthazard and Marcelle Lambert

Published a comprehensive study of hair

Dr. sydney smith

analyzed hairs side by side using a comparison mcroscope

Today

standard procedures of hair analysis include microscopic examination of DNA analysis

hair functions:

regulates body temperature, decreases friction, protects against sunlight, acts as a sense organ

humans are born with about _____ hair follicles

5 million

hair is composed of the protein __________

keratin

keratin is also a component of

finger and toe nails

hair is produced from a structure called the hair ___________

follicle

human develop hair during fetal development and ______

no new follicles are produced after birth

hair color is mostly a result of _______

pigments

pigments are

chemical compounds that reflect certain wavelengths of light

hair ________ and ________ is influenced by genes

shape, color

the physical appearance of hair can be affected by

nutritional status and intentional alteration (dyes)

the body area from which hair originated from can be determined by the sample's

length, shape, size, color, and other physical components

human hair consists of

a follicle and a shaft

human hair originates in the ___________ layer

dermis

it is attached to a

sebaceous oil gland

the cortex gives hair its_____

shape

what takes up most space in a human hair

cortex

the two major characteristics of the cortex are

melanin: pigment granulates that give hair its color

cortical fusi: air spaces, near the root but may be found throughout

in humans, hair varies from person to person, and even varies _______

depending on its location

for an individual person, hair can

vary based on location

to compensate for inconsistencies that occur, _______________ are usually collected rom a suspect's or victim's hair

3-50 hairs

hair can be ______________ depending on the cross-section

straight, curly, or kinky

cross section of a hair may be

round, oval, or crescent-shaped

hair wave or curl patterns are based on

the shape of the follicle that the hair comes from

pubic hair is identifiable since it is

dent slightly near the root

beard hair is identifiable since it

contains a double medulla

arm/leg hair is identifiable since it has

split ends, and may contain a burnt edge (from shaving)

hair proceeds through _____________ stages as it develops

3

what is the antigen phase and how long does it last

hair is actively growing; lasts up to 5 years but usually lasts around 3

what is the catagen

hair does grow and the follicle recedes

what is the telogen phase and how long does it last

follicle is ready to push the hair out, easily lost; lasts about 2-6 months

hair grows about 0.4 mm per _________ or 1/2 inch per ____________

day; month

human roots look different based on whether

they have been forcibly removed or hairs that have undergone telogen and have fallen out

animal roots vary but in general have a

spear shape

naturally shed hairs dislodged through combing display ____________

undamaged, club-shaped root

a hair forcibly removed from the scalp will exhibit ____________

stretching and damage to the root area

forcibly removed hairs may have ____________

tissue attached, called the follicle tag

post mortem root is also known as __________

dead man's root

post mortem root is _______

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

bleached hair lacks __________

pigment in the cortex and cuticle

dyed hair

stains the whole hair, including the cuticle and cortex

pigment granules are

absent in grey hair

why test hair

easy to collect and store

externally available

provide evidence of drug abuse and poison

collections must be taken from locations on the body to get ____

an accurate timeline

Drugs can be detected in hair for

years

animal hair and human hair have several differences including

pigmentation

medullary index

and cuticle type

what is a fiber

the smallest unit of a textile (a cloth of woven fabric) material that has a length many times greater than its diameter

fibers can occur _______________ but they can also be __________

naturally as plan or animal fibers; man-made (synthetic)

A fiber can be __________ that can be woven or knitted to form a fabric

spun with other fabrics to form a yarn

Fibers especially those that are too short in their raw statements are ______________ which are woven into _________

spun into yarn; textiles

the warp is

the arrangement of fibers running lengthwise

the weft

the arrangement of fibers running crosswise

yarn is

a continuous strand of fibers or filaments that may be twisted together

warp is

lengthwise yarn

weft is

crosswise yarn

blend is

a fabric made up of two or more difference types of fibers

weave patterns are

the patterns in which the weft passes over and under the wrap

many natural fibers that come from plants, animals, and minerals are __________

used in the production of fabric

fibers are composed of _________

polymers which are long repeating molecules of monomer building blocks

cotton fibers are the plant fibers most commonly used _____________

in textile materials

three sources of animal fibers are _________, _________, and _________

hair, fur, and webbing

all animal fibers are made of

proteins

the animal fibers most frequently used in the production of textile material is ________

wool

the most common wool fibers originate from __________

sheep

plant fiber is made of the polymer ___________

cellulose

cellulose is made up of

simple glucose monomers

plant fibers can

absorb water

insoluable to water

very resistant to damage from harsh chemicals

plant fibers can only be dissolved by

strong acids

plant fibers may be common at crime scenes because

they become brittle over time

cotton from seedpods is the plant fiber ___________

most commonly used in textiles

coir from coconuts is durable and

water proof

__________________ from stems frow in bundles

hemp, jute, and falx

manila and sisal from leaves __________

deteriorates more quickly

not all minerals are

long and repeating polymers

_______________ is a naturally occurring mineral with a crystalline structure

asbestos

until the 19th century only ______________ were used to make clothes and textiles

plant and animal fibers

half the products produced today are ____________

artificially produced

nylon, rayon, and polyester are all examples of

synthetic fibers

synthetic fibers are stronger than

the strongest natural fibers

manufactured fibers are not damaged by ____________

microorganisms

manufactured fibers can deteriorate in _______________, and they ____________ than natural fibers

bright sunlight; melt at a lower temperature

weaving consists of

arranging lengthwise threads side by side and close together. Than crosswise threads are then woven back and forth in one of several different patterns

fabrics differ by _____________________

weave pattern, thread count, two ply

fiber identification using various ________________________ is possible

microscope, gas chromatography, and mass spectrometer

primary transfer occurs from _______________

victim to suspect or suspect to victim

secondary transfer occurs from _______________

a source to the victim to the suspect

list five ways fibers are collected

Special vacuums

sticky tape

forceps

black lights

magnifying glasses

the value of evidence depends on its _________________

Uniqueness (color, type, frequency, location, textile of origin, type of crime, and time between collection and the time of the crime.)

when should a fiber sample be collected

as soon as possible

it is estimated that ___________ percent of all fibers may have fallen from a victim or suspect after 24 hours

95

dead bodies are no longer covered in cotton because ___________

fibers between the cotton, clothes, and body would get contaminated and would lead do destruction of evidence

Which weave pattern is this?

Plain - Alternating warp and weft threads

Which weave pattern is this?

Basket

Which weave pattern is this?

Satin