Hair and Fibers Forensics, Forensic Science Exam Study Guide- Hair, Fiber, and Physical Evidence

What are the differences between human hair and animal fur?

- Medulla in a human is smaller (medullary index of less than one-third); and medulla in animals is very thick (medullary index of one-half or greater). - 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.

Micrscopic characteristics of hair include

-presence of the medulla and its thickness -the color of the cortex

What are the four layers of car paint?

A typical automotive coating system consists of four layers as shown in Fig. 1, namely the e-coat, the primer or filler, the basecoat and the clearcoat, and the latter two-layers are combined into the topcoat.

What is laminated glass and what does it do?

Laminated glass is a type of safety glass that holds together when shattered.

What is glass made out of?

Liquid Sand

What is the ovoid body, cuticle, medullaand cortex of hair?

Ovoid bodies - It may contain cortical fusi, pigment granules, and/or large oval-to-round-shaped structures. Are found mostly in dog hair and cattle, but present in some human hair cuticle- transparent outer layer of hair shaft made of overlapping scales that protect inner layers cortex- largest part of hair shaft that contains most of melanin granules that give hair its color medulla- the center of hair. Can be hollow, absent, fragmented, segmented, continuous, double, etc

What is paint made out of?

Paint typically consists of pigment, resin, solvent and additives:

What is trace evidence and physical evidence?

Physical evidence: is any material object that plays some role in the matter that gave rise to the litigation, introduced as evidence Trace evidence: any material transferred between people, objects or the environment during a crime.

What is the chemical composition of hair?

Protein, moisture, lipids, pigment, minerals, carbohydrates

How can you tell the sequence of events in broken glass?

Sequence of force determination: An examiner can establish the sequence of the shots by considering the radial fracture's termination points. The first shot's radial fractures will extend completely while the subsequent shots' radial fractures will be stopped or cut off as they come into contact with prior fractures.

Fiber is collected at a crime scene. When viewed under a microscope what two traits would indicate that the fiber was human hair and not from an article of clothing?

Shape of the follicle and the size of the medulla

What is palynology?

Study of pollen and spores based on characteristics

A strand of hair has what two external parts

The cuticle and the hair shaft

Hair collected at a crime scene would be individual when/ which branch of the labeling tree

The hair with the follicle because you can pull DNA from it 3rd Branch (PCI)

Hair collected at a crime scene would be class when/ which branch of the labeling tree

The hair without the follicle 2nd branch

What are the types of fibers?

The most common animal fiber is sheep wool, but this category could include fibers from other animals, including mohair, cashmere, alpaca, and camel. More than half the fibers used in the production of textiles are synthetic, and include nylon, rayon, and polyester

True or False: All hairs on the head of the person are identical.

False

True or False: Hair with the follicle is direct evidence

False

true or false Hair is composed of Cellulose?

False

What structure does a glass hold ?

Glass is an amorphous or non-crystalline solid that is brittle in nature and the structure is obtained by melt-quenching process.

What is the importance of the scale pattern on hair?

Helps determine if hair is human or animal fur

Human hair has which type of cuticle? a. imbricate b. spinous c. coronal d. pigmented

a. imbricante

The hair shaft is composed of the cuticle, cortex, and the a. medulla b. root c. crown d. granules

a. medulla

Neutron activation analysis can check hair for the presence of a. silver b. Dna c. water content d. hair dye

a. silver

Hair collected at a crime scene would be physical when/ which branch of the labeling tree

it is just a piece of hair found 1st branch

What is a radiating fracture? What is a concentric fracture?

1st : Radiating Fracture: radiating lines dispersing outward from impact site. spider like line 2nd: Concentric Fracture: fractures forming in an ap proximately circular pattern around the point of impact.

Which observations are used to help identify a specific fiber: a. smell of the burned fiber 2. weave pattern 3. reactions to chemical liquids 4. all of the above

4. all of the above

Fiber is collected at a crime scene. When viewed under a microscope, what two traits would indicate the fiber was human hair and not from an article of clothing? a. presence of cuticle b. medullary index of .33 or less c. wide diameter d. ability to dissolve in water

A AND B (medullary index and presence of a cuticle)

What are the phrases of hair development?

The three stages of hair growth are the anagen, catagen, and telogen phases

True or False: The shaft of the hair is considered class evidence.

True

True or false: The cortex may contain pigment granules

True

The stages of hair growth

anagen (growth), catagen (growth and change), telogen (dormant) stages.

Which part of the hair can be analyzed for DNA? a. cuticle b. root c. medulla d. cortex

b. root

Two other methods that can analyze fivers desires macroscopic and microscopic observations include:

burning fibers and dissolving the fibers in various liquids

The period of active hair growth is called the a. catagen stage b. telogen stage c. anagen stage d. imagen stage

c. anlagen stage

Fibers are an excellent source of trace evidence because a. They are easily transferred from victim to suspect b. They are often overlooked by a suspect c. They are easily collected and stored D. All of they above

d. all of the above

Animal hair and human hair differ based on a. color pattern b. medulla size c. scale pattern d. all of the above

d. all of they above

Which factors are used to calculate the medullary index of the hair? a. scale diameter of the cuticle and length of the hair b. width of cortex and the width of the medulla c. length of entire hair and the pattern of the pigmentation d. width of medulla and the width of the hair

d. with of the medulla and the width of the entire hair

Differences between animal and human hair types include:

differences in pattern, pigmentation, medullary index, and cuticle type.

What gives glass different colors and strengths?

elements are added in holding color properties.

Synthetic fibers include

man made and regenerated fibers

What is a physical and chemical change?

physical change: a change in only appearance Chemical change: a permanent change in chemical composition

Natural fibers come from

plants ,animals, minerals

Natural Fibers cane one harvested from

plants and animals

The Hair shaft....

protrudes from the skin surface and isn't embedded in the skin

What are the three main categories of soil?

sand, silt and clay.

Types of Fibers are classified as

synthetic or natural

From class classified hair you can determine

the color from the medulla and if the hair is curly or straight