Comparison of Animal Cuticle scales http:www.rit.edubekpphsemProjectsReich Also remember Koality Ass

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Comparison of Animal Cuticle scales
http//www.rit.edu/bekpph/sem/Projects/Reich/Als
o remember Koality Assurance
Cat
Rabbit
Rat
Human
Dog
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CORTEX

• Forensic Significance
• Its embedded with the pigment granules that
  impart hair with color
• The color, shape and distribution of these
  granules that provide examiners with many points
  of comparison between hairs of individuals

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Medulla

• The medulla may vary in thickness, continuity
  (one continuous structure interrupted into
  pieces), and opacity (how much light is able to
  pass through it)
• continuous medulla
• interrupted medulla
• Fragmented medulla
• May also be absent. Like the cuticle, the medulla
  can be important for
• Distinguishing between hairs of different
  species, but often does not lend much to human
  hair

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HUMAN VS ANIMAL

• ANIMAL
• -diameter of animal
• widens then narrows
• - medullas occupy
• more than ½ of
• diameter
• - display ladder-like
• patterns
• - cuticles are coarse

• HUMAN
• - diameter is uniform
• - medullas occupy no
• more than 1/3 of
• diameter
• - never display ladder-
• like patterns
• - cuticles are relatively
• smooth

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ROOT

• Cells in root and around follicle provide growth
• Three stages of development
• Anagen- (approx. 6 yrs) initial growth phase,
  when pulled good chance of follicular tag-tissue/
  important for DNA analysis
• Catagen- root bulb shrinks in this transition
  phase
• Telogen- Hair is pushed out of the follicle and
  rood takes on a club-shaped

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Three Stages of Hair Growth
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Hair Collection

• When questioned hairs are submitted must have
  plenty of Controls
• Head hairs 50 hairs from different areas
• Pubic Area 24 hairs
• Should be pulled or cut at scalp/skin line

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Hair Root with Tissue Attached contains DNA
ROOT
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Hair Evidence

• Human or non-human?
• Body part origin (scalp, pubic, limb)
• Forcibly removed?
• DNA on root tissue
• Microscopic Examination

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FIBER EVIDENCE

• Commonly in incidents which involve personal
  contact
• Homicide
• Assault
• Sexual Offenses
• Anywhere there maybe a cross-transfer

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Fiber Evidence

• Sources apparel, bedding, carpet (flooring and
  automobile)
• Mixtures (gray sweatshirt black rayon and white
  cotton)
• Dyes

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Two Broad Groups

• Natural Fibers
• Animal
• Wool, cashmere, fur (mink, rabbit...)
• Plant
• Cotton
• Almost meaningless unless dyed and in a
  combination of colors

• Man Made Fibers
• Derived from natural or synthetic polymers
• Polymer is the basic chemical substance of all
  synthetic fibers
• Made of Monomers

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FIBER ANALYSIS

• NATURAL FIBERS derived from animal or plant
  sources
• - animal comprise the majority of natural fibers
  seen in the laboratory (wool)
• - most prevalent plant fiber is cotton

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MAN- MADE FIBERS

• Regenerated fibers manufactured from raw
  materials derived from cotton or wood pulp
• - rayon
• -acetate
• -triacetate

• Synthetic fibers manufactured from synthetic
  (man-made) chemicals
• - nylons, polyesters,
• and acrylics
• polymers basic
• substance of all
• synthetic fibers

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LABORATORY EXAMS

• Examinations vary so much from crime laboratory
  to crime laboratory and from analyst to analyst.
• Consistent forensic analysis
• - compare color
• - compare diameter
• Scanning Electron Microscope

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Examining Color Diameter

• Under Microscope fibers may appear to have same
  color
• However dyes applied by manufacture may have a
  different composition
• Microspectrophotometer
• Non destructive way to compare colors
• Various shapes / diameter
• Trilobal fibers
• Presence or absence of a delustering agent
• Titanium dioxide