Chapter 3 forensics

What's the medullary index of human hair?

.33 or less, evenly distributed granules

How does albino hair and brown hair contrast

Albino hair contains Unpigmented medullas and also has less melanin than a person with brown hair in the cortex

Psychical evidence

All objects that can establish that a crime has been committed or can provide a link between crime and victim or victim and perpetrator

Hair is composed of what protein?

Keratin

The hair shaft is composed of the cuticle, cortex, and

Medulla

What is melanin?

Melanin produces the color in hair

Cortex

Melanin-containing, colored layer of hair shaft

Can you directly prove that a fiber came from one place?

No

Individual evidence

Originates from a single source

What characteristics do you look for in hair?

Pigmentation, cortex, cuticle, medulla

Human hair has which types of cuticle

Pigmented

Cuticle

Scales protecting inner layers of hair, scales point towards end of hair

Fiber

Smallest unit of a material that has a length many times greater than its diameter

What's the difference between synthetic and natural fibers?

Synthetic fibers are not tarnished by insects, synthetic fibers are man made, natural come from nature, after burning synthetic smells like chemicals while natural smells like camp fire

All hairs on a person's head is identical

False

Which of the following characteristics is found in typical Asian hair?

Flattened cross section

Comparison microscope

a compound microscope that allows the side-by-side comparison of samples, such as of hair or fibers

Individual evidence

a kind of evidence that identifies a particular person or thing

Neuron activation analysis

a method of analysis that determines com- position of elements in a sample

Keratin

a type of fibrous protein that makes up the majority of the cortex of a hair

Cuticle

the tough outer covering of a hair composed of overlap- ping scales

Class evidence

Evidence that can only be associated with a group and not a single source, for example hair

Medulla

Central layer of the hair shaft

Is hair trace or class evidence?

Class evidence

Hair

Composted of keratin

If you were to take a piece of your hair and put it under a microscope what would it look like?

Coronal scale pattern, straight, blonde, continuos amorphous.

Medulla

Determines whether animal or human

What are the differences between animal hair and human hair

There's differences in pattern, pigmentation, medullary index, and cuticle type.

Is fiber class or trace evidence?

Trace

The cortex may contain pigment granules

True

The shaft of the hair is considered class evidence in a trial

True

Which factors are used to calculate the medullary index of the hair?

Width of medulla and width of hair

Melanin granules

bits of pigment found in the cortex of a hair

Class evidence

material that connects an individual or thing to a certain group

Trace evidence

small but measurable amounts of physical or biological material found at a crime scene

Hair follicle

the actively growing root or base of a hair containing DNA and living cells

Medulla

the central core of a hair fiber

Cortex

the region of a hair located outside of the medulla containing granules of pigment