Chapter 5: Hair

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Chapter 5Hair

• For three days after death, hair and fingernails
  continue to grow but
• phone calls taper off.
• Johnny Carson
• Comedian and television host

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Introduction

• Human hair- one of the most frequently found
  pieces of evidence
• Provides a link between the criminal and the
  crime
• From hair one can determine
• If the source is human or animal
• Race (sometimes)
• Origin of the location on the sources body
• Whether the hair was forcibly removed
• If the hair has been treated with chemicals
• If drugs have been ingested

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About Hair

• Amount
• Blonds have the most 120,000 strands
• Redheads have the least 80,000
• Brunets 100,000
• Grows from follicle
• Tube-like organ where root grows from
• Linked to blood supply
• Important if looking for poisons or drugs
• Except for the follicle, hair is made of dead
  cells
• Hair is constantly shed from body

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Skin Structure
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Hair Shaft

• Composed of polymers of keratin
• Large molecule with repeating units
• Cuticleoutside covering, made of overlapping
  scales
• Cortexinner layer made of keratin and imbedded
  with pigment also contains air sacs called
  cortical fusi
• Medullainside layer running down the center of
  the cortex

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The Cuticle

• Outermost layer
• Covered in scales
• The scales point toward the tip of the hair
• Scales differ between species of animals
• The three basic patterns are
• Coronal
• Spinous
• Imbricate

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Coronal

• Look like stacked cups
• Found in rodents and bats
• Rarely in humans

Bat Tail Hair
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Spinous

• Petal shaped- triangular
• Point away from shaft
• Never found in humans
• Fur of mink, cats, seals, other small animals

Mink Hair
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Imbricate

• Overlapping scales, AKA flattened
• Human and many animal hairs
• Good website

Mink Hair
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Human Scales

• In order to visualize the
• scales
• paint clear fingernail polish on a glass slide
• when the polish begins to dry, place a hair on
  the polish
• when almost dry, lift off the hair and observe
  the scale imprints
• What pattern is seen in
• this slide?

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The Medulla

• Hair core
• Comes in different types and patterns
• Row of cells along the cortex
• Usually not found in humans, mostly animals
• If it is present, it is fragmented or interrupted

• Types
• Intermittent or interrupted
• Fragmented
• Continuous
• Stacked
• Absentnot present

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Name that Pattern!
Fragmented- Cat Hair
Continuous- Horse Hair
Stacked- Mouse Hair
Continuous- Cow Hair
Absent- Human Hair
Interrupted- Cat Hair
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Name That Animal!

• Cat

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Name That Animal!

• Cow

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Name That Animal!

• Deer

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Name That Animal!

• Dog

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Name That Animal!

• Horse

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Name That Animal!

• Mouse

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Name That Animal!

• Pig

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Name That Animal!

• Rabbit

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Name That Animal!

• Squirrel

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Name That Animal!

• Human

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• For more pictures http//www.bsapp.com/forensics_
  illustrated/photos/unit_5_photos.htm
• Hair ID activity
• Hair ID quiz

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Medullary Index

• Determined by measuring the diameter of the
  medulla and dividing it by the diameter of the
  hair.
• Medullary Index for human hair is generally less
  than 1/3.
• For animal hair, it is usually greater than 1/2.

mouse
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The Cortex

• The cortex gives the hair shape
• Main body of hair made from elongated cells
• It has two major characteristics
• Melaninpigment granules that give hair its color
• Cortical fusiair spaces, usually found near the
  root but may be found throughout the hair shaft
  give hair its characteristics

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Animal Vs Human

• Animal hairs are much more diverse than human
• One animal may contain several different kinds of
  hair
• Good website

Animal
Human

• Not uniform in color- banding
• Pigment gets lighter toward tip
• Larger medulla
• Roots vary
• Scales vary

• Uniform in color
• Smaller medulla
• Roots are club-shaped
• Usually imbricate

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Hair Shape

• In general, Asian and Native American backgrounds
  have round cross section and no twisting (curl)
• Caucasian, Mexican and Middle Eastern background
  usually oval sometimes undulated (wavy or curly)
• 25-125 micrometers in diameter

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Hair Shape

• Can be straight, curly or kinky depending on the
  cross-section, which may be round, oval or
  crescent-shaped

Crescent moon (Kinky)
Oval (Curly)
Round (Straight)
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Hair Growth

• Terminology
• Anagenhair that is actively growing lasting up
  to 5 years (90 of hair follicles)
• Catagenhair is not growing a resting phase
• Telogenhair that is dying and ready to fall out
  lasting two to six months (10 follicles)
• Grows about 0.5 mm per day or 1 centimeter per
  month approximately one half inch per month
• Grows from the root

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The Root

• Human roots look different - whether they have
  been forcibly removed or if they are telogen
  hairs and have fallen out.

Fallen out
Forcibly removed
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Fallen Out Hairs
bsapp.com
32
Natural Tip
bsapp.com
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Pulled Out-By the Root
bsapp.com
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Broken-Torn
bsapp.com
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Cut Hair
bsapp.com
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Hair Comparison
Ways to compare human hair

• Color
• Length
• Diameter
• Distribution, shape and color intensity of
  pigment granules
• Dyed hair has color in cuticle and cortex
• Bleaching removes pigment and gives a yellow tint

• Scale types
• Presence or absence of medulla
• Medullary type
• Medullary pattern
• Medullary index

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DNA from Hair

• The root contains nuclear DNA
• Forcibly removed- some tissue may be attached
  containing DNA
• Abundant mitochondrial DNA, inherited only from
  the mother
• It can be typed by comparing relatives if no DNA
  from the body is available.
• This process is more difficult and costly than
  using nuclear DNA.

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Collection of Hair

• Questioned hairs must be accompanied by an
  adequate number of control samples.
• from victim
• from possible suspects
• from others who may have deposited hair at the
  scene
• Control Sample
• 50 full-length hairs from all areas of scalp
• 24 full-length pubic hairs

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Hair Toxicology

• Advantages
• Easy to collect and store
• Is externally available
• Can provide information on the individuals
  history of drug use or of poisoning.
• Collections must be taken from different
  locations on the body to get an accurate timeline.

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Hair Toxicology

• Drug analysis of hair backs up blood and urine
  tests because the drugs last long in the hair
• Show environmental factors if a person is in a
  smoky environment, it might appear as if they
  smoke
• False Positive test that comes out positive but
  should not

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Hair Dyes

• Can be detected with infrared detectors
• Example ½ inch a month, on inch segment of
  unbleached hair means the last treatment was two
  months earlier

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Hair Toxicology

• Napoleon died in exile in 1821. By analyzing his
  hair, some investigators suggest he was poisoned
  by the deliberate administration of arsenic
  others suggest that it was vapors from the dyes
  in the wallpaper that did him in.

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More about Hair

• For additional information about hair and other
  trace evidence, check out Court TVs Crime
  Library at
• www.crimelibrary.com/criminal_mind/forensics/tr
  ace/1.html