Study Guide Hair Unit

Question 1

What categories of evidence does hair belong?

Answer 1

Class and circumstantial evidence

Question 2

What types of information can be determined from a hair sample?

Answer 2

If the source is human or animal, race (sometimes), origin of the location on the source’s body, whether the hair was forcibly removed, if the hair has been treated with chemicals, if drugs have been ingested

Question 3

From which layer of skin does hair originate?

Answer 3

The epidermis

Question 4

Describe the different part of a single hair?

Answer 4

Hair shaft: the cuticle, cortex and medulla. The follicle and the root.

Question 5

Describe the layers of a hair from the outside going in.

Answer 5

First is the cuticle, which is the outermost layer of hair that is covered in scales that point to the tip of hair.

Then, there is the cortex which gives the hair its shape. It includes melanin, which gives the hair its color, and cortical fusi, which are air spaces found near the root but may not be found throughout the hair shaft.

Finally, there is the medulla which is the hair core that is not always visible.

Question 6

Draw and describe the three different types of the cuticle.

Answer 6

Coronal: a crown like pattern that resembles paper cups.
Spinous: Petal-like scales are triangular in shape and stick out from the hair shaft.
Imbricate: overlapping in sequence, as tiles or shingles on a roof.

Question 7

Describe the process to create a slide that will show the cuticle pattern from a hair.

Answer 7

1. Paint clear fingernail polish on a glass slide
2. When the polish begins to dry, place a hair on the polish
3. When it is almost dry, lift off the hair and observe the scale imprints
   NOTE: Imbricate can be seen with this method

Question 8

What are the two parts of the cortex and how are they different?

Answer 8

Melanin are pigment granules that give the hair its color, while cortical fusi are air spaces, usually found near the root but may be found throughout the hair shaft

Question 9

What is the medulla and what are the different patterns of medulla found in hair?

Answer 9

The medulla is the hair core that is not always visible. The medulla comes in different types and patterns. It may be continuous, fragmented or absent.

Question 10

How can you tell the difference between human hair and animal hair?

Answer 10

Medullary index for human hair is generally less than 1/3, while it is greater than 1/2 for animals.
Cuticle in humans is imbricated; and the cuticle in animals is coronal or spinous. - Pigmentation in animal hair is denser than human hair. - Animal hair can change colors in banded patterns; human hair cannot.

Question 11

What is the medullary index and how is it calculated?

Answer 11

The medullary index describes the thickness of the medulla layer that is present. It is determined by measuring the diameter of the medulla and dividing it by the diameter of the hair.

Question 12

What determines the shape of the hair?

Answer 12

It can be straight, curly, or kinky, depending on the cross section, which may be round, oval, or crescent shaped.

Question 13

Anagen

Answer 13

hair is actively growing; lasts up to 2-6 years (85% of head hairs)

Question 14

Catagen

Answer 14

hair is not growing; a resting phase (2 weeks) blood supply is cut off

Question 15

Telogen

Answer 15

follicle is getting ready to push the hair out; lasts 1-4 months (10-15% of head hairs)

Question 16

Describe the difference in a root found that has been forcibly removed and has fallen out naturally.

Answer 16

Hair that has fallen out naturally, the root looks smooth in appearance. If hair has been forcibly removed, the root will not appear smooth under the microscope

Question 17

What differences do investigators look for when comparing two different hair samples.

Answer 17

Color, length, diameter, distribution, shape, color intensity, scale types, presence/absence of medulla, medullary type and pattern and index

Question 18

Where is the DNA found in a hair?

Answer 18

The root contains nuclear DNA. The hair shaft contains abundant mitochondrial DNA, inherited only from mother

Question 19

Describe the types of hair samples and the total number of hairs required by investigators at a crime scene

Answer 19

Questioned hairs must be accompanied by an adequate number of control samples from victim, possible suspects, others who may have deposited hair at the scene.
Control sample- 50 full-length hairs from all areas of scalp, 24 full length pubic hairs

Question 20

How is hair a good record of drug use or poisoning?

Answer 20

It is easy to collect and store, is externally available, can provide information on the individual’s history of drug use or evidence of poisoning, collections must be taken from different locations on the body to get an accurate timeline

Question 21

How do investigators use fibers as a link in a crime scene?

Answer 21

Very small fibers are classified as trace evidence. Fiber evaluation can show type of fiber, color, possibility of violence, location of suspects, point of origin

Question 22

How are fiber and material samples collected then analyzed as evidence?

Answer 22

Shedding- common form of fiber transfer
Microscopes reveal characteristic shapes and markings
Infrared spectroscopy reveals chemical structures to differentiate similar fibers
Destructive testing methods- burning fibers and dissolving fibers in various liquids
Compare fibers found on different suspects with those found at the crime scene

Question 23

Describe the four types of macromolecules that are biologically important and how are these molecules put together to make polymers and the functions of each.

Answer 23

Lipids (does not form polymers).Function: move and store energy, absorb vitamins and make hormones
Nucleic Acids- monomers: nucleotides, polymer: DNA/RNA, Function: Hereditary information.
Carbohydrates- monomers (single sugars/monosaccharides), polymer (polysaccharides), animals: glycogen (energy storage), plants: starch (energy storage) and cellulose (structural), function is energy storage/cell-cell recognition.
Proteins- monomer (amino acids), polymer (polypeptide chain- protein), function is structural support, storage, transport, cellular communications, movement and defense against foreign substances, hair is made of protein

Question 24

The characteristics of plant fiber, including the aroma while burning and its appearance under a microscope?

Answer 24

Absorbs water, insoluble in water, resistant to damage from chemicals, dissolvable only from strong acids. It ignites quickly and burns easily, giving off a smell of burnt paper, leaves or wood and results in flaky, ashy remains. Look like small donuts within a cross-section

Question 25

The characteristics of animal fiber, including the aroma while burning and its appearance under a microscope?

Answer 25

Made of proteins, insulating properties, resists wrinkling, a strong odor of burning hair. Scaly corkscrews.

Question 26

The characteristics of mineral fiber, including the aroma while burning and its appearance under a microscope?

Answer 26

Resistant to chemical attack, insulating qualities, nonflammable, doesn’t deteriorate in normal usage, burnt cookies, burnt cotton candy, and burnt glue. Consistent cross section.

Question 27

Synthetic Fibers

Answer 27

made of large molecules formed during chemical processes called polymers. Examples of synthetic fibers include nylon, polyester, and acrylic

Question 28

Synthetic cellulose fibers

Answer 28

produced by processing various natural polymers

Question 29

Synthetic polymer fibers

Answer 29

petroleum base, very different from other fibers, made from monomers

Question 30

Plain/tabby

Answer 30

firm and wears well, snag resistant, low tear strength, tends to wrinkle

Question 31

Basket

Answer 31

open or porous weave, does not wrinkle, not very durable, tends to distort as yarns shift, shrinks when washed

Question 32

Satin

Answer 32

not durable, tends to snag and break during wear, shiny surface, high light reflectance, little friction with other garments

Question 33

Twill

Answer 33

very strong, dense and compact, different faces, diagonal design on surface, soft and pliable

Question 34

Leno

Answer 34

open weave, easily distorted with wear and washing, stretches in one direction only

Question 35

Define and sketch the Warp and Weft in a fabric

Answer 35

The vertical warp yarns are held stationary in tension on a loom (frame) while the horizontal weft (also called the woof) is drawn through (inserted over and under) the warp thread

Question 36

Wayne Williams Case

Answer 36

He was convicted of two murders on February 27, 1982, after he was linked to the victims through meticulous hair and fiber analysis and witness testimony. Following the trial, the law enforcement task force concluded that there was enough evidence to link Williams to another 20 of the 29 deaths. He went to jail for life, and the Atlanta child killings stopped.

Question 37

Two in a Million Video (Silencer)

Answer 37

silencer made with tennis balls