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2 Main parts of hair
shaft and follicle
Hair evidence classification
Circumstantial, Biological, Class (if no follicle), Individual (if follicle is present)
What contains DNA in hair
follicle
Macroscopic characteristics of hair
Color, Texture, Length
Microscopic layers of hair
Cuticle, Cortex, Medulla
Hair: provides protection
Cuticle
Hair: provides strength, color, texture
Cortex
Hair: unknown function (absent, continuous, fragmented, interrupted)
Medulla
Regions of human body hair can be found
body, head, pubic, underarm, eyebrow, lash, beard, mushtache
How can hair be analyzed
DNA testing, Chemical testing, Microscopy
Protein that gives hair strength
Keratin
2 main types of fibers
Natural and Synthetic
Natural fibers
Plants
cotton
linen
Sheep
Wool
Caterpillar
Silk
Synthetic fibers
polyester
rayon
nylon
spandex
acrylic
Fiber evidence classification
Circumstantial, Biological (if plant, animal, or mineral), Physical (if synthetic), Class (if common fiber), individual (if rare fiber)
How can fibers be collected?
Tweezers, Vacuum, Adhesives
How to analyze fiber evidence
Microscope (nondestructive) and Burn test (destructive— only use if there is a lot of material)
Fiber characteristics
color, texture, thread count, shape, weave pattern, luster/shine
burn test characteristics
melt/burn, ignite/sputter, hard ball/brittle ash, smell of chemical/hair
Locard’s Exchange principle
states fibers can be transferred during criminal activity
Situations in which lots of fiber evidence would be transferred during a crime scene
violent and fighting crime, or long duration of crime
Fingerprint test reacts with amino acids in the oils of skin; prints turn golden
Iodine Fuming
White Crystal Test
Superglue fuming
Fingerprint test reacts with amino acids in oils of skin; print turns purple
Ninhydrin
IAFIS
(Integrated Automated Fingerprint Identification System): program that provides digital, automated fingerprint searches for the FBI