Hair Analysis

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Hair Analysis
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Hair

• One of the most frequently found pieces of
  evidence
• Provides strong collaborative evidence for
  placing a suspect at the crime scene
• Cannot be specifically linked to a particular
  individual

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Structure
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Cuticle

• Outer protective layer of hair consisting of
  scales
• 3 basic scale structures
• coronal-crown like
• spinous- petal like
• imbricate- flattened
• Can be used to differentiate species, but not to
  distinguish between hairs of the same species

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Coronal scales
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Spinous scales
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Imbricate scales
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Medulla

• The central core of cells that may be present
• Can be classified as
• Fragmented
• Intermittent
• continuous

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Medulla
fragmented
intermittent
continuous
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Cortex

• The main body of the hair
• Varies in thickness, texture, and color
• The color, shape, and distribution of pigment
  granules allow for forensic comparison
• Perhaps the most important component in
  determining from which individual a human hair
  may have come

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Cortex
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Differentiating

• Cat
• Dog
• Human

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Cat

• Diameter fine
• Medulla continous
• Scales spinous
• Pigment may be banded
• Root elongated

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Dog

• Diameter fine to coarse
• Medulla continuous
• Scales not prominent
• Pigment continuous, not banded
• Root spade shaped

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Human

• Diameter varies
• Medulla when present, is less than 1/3 the
  diameter, unlike animal hair not always
  continuous whereas animal hair is
• Scale imbricate
• Pigment continuous
• Root club shaped

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• Microscopic hair comparisons are presumptive
• Must be confirmed by DNA

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Online Sources

• http//www.nifs.com.au/FactFiles/HairFibre/how.asp
  ?pagehowtitleHair20and20Fibres
• http//www.fbi.gov/hq/lab/fsc/backissu/jan2004/res
  earch/2004_01_research01b.htm