the transfer of evidence such as a fiber from a source (for ex. a carpet) to a person (suspect) and then to another person (victim)
a compound microscope that allows the side-by-side comparison of samples, such as hair or fibers
one of the two main parts of hair, it is composed of the protein keratin, and it has three layers
the actively growing root or base of a hair containing dna and living cells
The network of blood vessels that supply nutrients to feed the hair and help it grow
secretes oil that helps keep the hair conditioned, it is associated with the bulb
the central core of a hair fiber
the region of hair located outside of the medulla containing granules of pigment
a type of fibrous protein that makes up the majority of the cortex of a hair
the tough outer covering of a hair composed of overlapping scales
pigments found in the cortex of a hair
Cuticle scales that are flattened and narrow in humans
neutron activation analysis
a method of analysis that determines composition of elements in a sample
Taylor and Stevenson
1883 wrote a forensics sciences text book that included a chapter on hair
Balthazard and Lambert
1910 published a comprehensive study of hair
Dr. Sydney Smith
1934 first used a comparison microscope to analyze hair side by side
Outer cuticle, cortex-surrounds the medulla
What is the structure of the hair shaft?
head, eyebrows and lashes, mustache and beard, underarm hair, overall body (auxilary hair) and pubic
What are the 6 different regions of body hair?
cross sections are circular or elliptical
What are the distinctions between cross sections of head hair?
cross sections are circular with tapered ends
What are the distinctions between cross sections of eyebrows and eyelashes?
cross sections are thick and triangular
What are the distinctions between cross sections of mustache and beard hair?
cross sections are oval or triangular
What are the distinctions between cross sections of body/pubic hair?
blunt ends and could be frayed from abrasion
What are the distinctions in arm and leg hair?
coarse and may have a double medulla
What are the distinctions in beard hair?
buckling may be present
What are the distinctions in pubic hair?
(~1000 days) actively growing stage, cells around the follicle rapidly divide and deposit materials in the hair, 80-90% of all human hair is in this stage
hair grows and changes, ~2% of all hair growth and development
when the follicle becomes dormant, hairs can easily be lost, 10-18% are in this stage
1.3 cm per month or .44 mm/day
How much does hair grow on average?
pigment is denser toward the medulla, pigments are often in solid masses (ovoid bodies), hair can abruptly change colors in banded patterns along the length of hair
How does ANIMAL hair differ from human hair?
pigment is denser toward the cuticle, hair is usually one color throughout the length
How does HUMAN hair differ from animal hair?
.5 or greater
What is the medullary index in animals?
.33 or less
What is the medullary index in humans?
ratio of diameter of the medulla to the diameter of the entire hair
spinous, coronal, imbricate
What are the types of cuticle scales?
What cuticle scales are found in cats, seals, and minks?
What cuticle scales are found in rodents and bats
What cuticle scales are found in humans
can indicate length, color, and curliness
can indicate fine detail in hair structure
phase contrast microscopy, fluorescence microscope, electron microscopes
What are the three types of microscopes for specialized techniques?
phase contrast microscopy
observes fine detail, focuses light that passes through objects of different refractive indexes, shows more contrast when viewing translucent particles
filters to detect fluorescent light; beam of light of a certain color is used, if sample contains particular chemicals, it will absorb some of the light and reemit light of a different color
direct beam of electrons at a sample, provides more detail of the surface or interior
Neutron Activation Analysis
can determine concentrations of substances in the sample
antimony, argon, bromine, copper, gold, manganese, silver, sodium, and zinc
What are the 9 different elements that Neutron Activation Analysis can identify?