Chapter 10: Hairs & Fibres

Question 1

Hair is what type of evidence?

Answer 1

Physical evidence

Question 2

Are you able to trace human hair back to the head it was on through morphology?

Answer 2

No

Question 3

What is another way to individual human hair?

Answer 3

Characterizing the DNA

Question 4

Hair samples from a crime scene are accompanied by what, when being sent to the lab?

Answer 4

Standard/reference samples

Question 5

How can hair provide a strong corroborative evidence?

Answer 5

Can place an individual at a crime scene

Question 6

Where does hair grow from?

Answer 6

Hair is an appendage of the skin that grows out of the hair follicle

Question 7

What are the 3 phases of hair growth?

Answer 7

• Anagen
• Catagen
• Telogen

Question 8

What are the 3 parts of the hair?

Answer 8

• Root/bulb
• Shaft
• Tip

Question 9

What are the 3 layers of the shaft?

Answer 9

• Cuticle
• Cortex,
• Medulla – that is subjected to the most intense examination by the forensic scientist.

Question 10

What is the cuticle of the hair?

Answer 10

The cuticle is the scale structure covering the exterior of the hair.

Question 11

The scale pattern of the hair cuticle points in what direction?

Answer 11

Points towards the tip

Question 12

How can you identify the species of hair?

Answer 12

The cuticle pattern

Question 13

What is the cortex?

Answer 13

The cortex is the main body of the hair shaft.

Question 14

How is the cortex important to forensics?

Answer 14

Its major forensic importance is the fact that it is embedded with the pigment granules that impart hair with colour.

Question 15

Pigment granules are absent in what colour hair?

Answer 15

Grey hairs

Question 16

What is the medulla?

Answer 16

The medulla is a cellular column running through the centre of the hair

Question 17

What is the medulla index?

Answer 17

The medullary index measures the diameter of the medulla relative to the diameter of the hair shaft.

Question 18

For human how much space does the medulla occupy?

Answer 18

For humans, the medulla generally occupies less than one-third the diameter of the shaft

Question 19

What is the follicular tag?

Answer 19

When pulled from the head, some translucent tissue surrounding the hair’s shaft near the root may be found.

Question 20

What can you use the follicular tag?

Answer 20

By using DNA analysis on the follicular tag, the hair may be individualized.

Question 21

What does the root provide?

Answer 21

Provides the tools necessary to produce hair and continue its growth.

Question 22

What is important features to identify in animal hair?

Answer 22

• Scale structure
• Medullary index,
• Medullary shape

Question 23

What type of microscope is used to compare characteristics of hair?

Answer 23

The comparison microscope

Question 24

When comparing strands of human hair, the criminalist is interested in matching…

Answer 24

• Colour
• Length
• Diameter

Question 25

Can the body area from which a hair originated be determined?

Answer 25

Yes. Based on the characteristics

Question 26

Can the racial origin of hair be determined?

Answer 26

Yes.

Question 27

Can the age and sex of an individual be determined from a hair sample?

Answer 27

Age cannot be determined

Sex can be if the cells are attached

Question 28

Is it possible to determine if a hair was forcibly removed from the body?

Answer 28

Yes

Question 29

At what hair growth stage is ideal for detecting DNA?

Answer 29

Anagen or early growth phase

Question 30

Where does mitochondrial DNA come from?

Answer 30

Hair shaft

Question 31

How is mitochondrial DNA transmitted?

Answer 31

From mother to child

Question 32

Forensic hair comparison involves what 2 types of hair?

Answer 32

• Head hair
• Pubic hair

Question 33

How many strands of hair is considered a sufficient sample?

Answer 33

25

Question 34

What are examples of natural fibres?

Answer 34

• Wool
• Mohair
• Cashmere
• Furs
• Cotton

Question 35

What are regenerated fibers?

Answer 35

Are manufactured from natural raw materials and include rayon, acetate, and triacetate.

Question 36

What are synthetic fibers?

Answer 36

• Are produced solely from synthetic chemicals and include nylons, polyesters, and acrylics.
• Synthetic fibers are composed of polymers, or macromolecules, which are a large number of atoms arranged in repeating units known as monomers

Question 37

What are morphological features important in comparing fibres?

Answer 37

• Colour
• Diameter
• Lengthwise striations on the surface of the fiber
• The presence of delustering particles that reduce shine
• The cross sectional shape of the fiber

Question 38

What is Infrared spectrophotometry?

Answer 38

Is a rapid and reliable method for identifying the generic class of fibers.

Question 39

What is a microspectrophotometer and what does it do?

Answer 39

Combines a traditional light microscope and a spectrophotometer. It allows a forensic analyst to view an object under a microscope while simultaneously obtaining its visible or infrared absorption pattern

Question 40

What is used to compare the colours of fibers through spectral patterns?

Answer 40

Microspectrophotometer

Question 41

Under a polarizing microscope what physical properties do many synthetic fibers exhibit?

Answer 41

Double refraction or birefringence

Question 42

True or false? Relevant articles of clothing (in relation to the hairs) should be packaged carefully in separate bags.

Answer 42

True

Question 43

If it is necessary to remove a fiber from an object, how is this process done properly?

Answer 43

• the investigator must use clean forceps
• place it in a small sheet of paper
• fold and label the paper
• place the paper packet inside another container.