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
