Transcript No Slide Title

TYPES OF HAIRS
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Primordial hairs - appear
as early as the
beginning of the third
month of gestation;
grows on the upper lip,
eyebrows, palms and
soles of the fetus.
Lanugo hairs - found in
fetal life, are shed after
the sixth month of
gestation, and are often
found on aborted
fetuses.
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Vellus hairs - are spread
uniformly over the
body’s surface, except
the soles of the feet.
Terminal hairs - replace
the vellus hairs at
specific sites and points
of life; are found mainly
on the scalp, on the
face, chest, back, arms,
and legs, and are sexlimited.
HAIR STRUCTURE
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Hair is an appendage of the skin that grows
out of the hair follicle.
Hair is composed of a group of keratins that
interacts and interconnect to from stable
fibrils, and is comprised of:
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Cuticle
Cortex
Medulla
HAIR STRUCTURE
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Diagram of Hair in Skin
HAIR STRUCTURE
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Cuticle - a thin translucent layer
surrounding the hair shaft.
consists of overlapping, non-nucleated,
pigment-free cells which form scales.
 the scales point away from the root
towards the tip of the hair shaft.
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HAIR STRUCTURE
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Cuticle Structure
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Coronal
HAIR STRUCTURE
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Cuticle Structure
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Spinous
HAIR STRUCTURE
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Cuticle Structure
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Imbricate
HAIR STRUCTURE
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Medulla - a cellular column running
through the center of the cortex.
Its presence varies from person to
person and between hair of a given
individual.
 The medulla originates from matrix
cells closest to the dermal papilla,
and large amounts of glycogen are
found in medullary cells.
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HAIR STRUCTURE
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Medulla (continued).
Main function is to increase the
protective properties of the hair by
adding internal air spaces to the hair.
 It occupies about one-third of the hair’s
width.
 Can be classified as absent,
fragmented, discontinuous, or
continuous.
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Medulla Structure
HAIR STRUCTURE
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Cortex
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The cortex is the main body of the hair
composed of elongated and fusiform
(spindle-shaped) cells. It may contain
cortical fusi, pigment granules, and/or large
oval-to-round-shaped structures called
ovoid bodies.
HAIR STRUCTURE
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Cortex
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Cortical fusi are irregularshaped airspaces of
varying sizes. They are
commonly found near the
root of a mature human
hair, although they may be
present throughout the
length of the hair
HAIR STRUCTURE
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Cortex
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Pigment granules are small, dark, and solid
structures that are granular in appearance
and considerably smaller than cortical fusi.
They vary in color, size, and distribution in a
single hair.
HAIR STRUCTURE
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Cortex
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In humans, pigment
granules are commonly
distributed toward the
cuticle as shown in except
in red-haired individuals.
HAIR STRUCTURE
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Cortex
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Animal hairs have the pigment
granules commonly distributed
toward the medulla.
HAIR STRUCTURE
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Cortex
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Ovoid bodies are large (larger
than pigment granules), solid
structures that are spherical to
oval in shape, with very regular
margins. They are abundant in
some cattle and dog hairs as
well as in other animal hairs.
HAIR STRUCTURE
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Cortex
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Ovoid bodies are also found in human
hairs.
GROWTH AND REPLACEMENT OF
HAIR
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Mammalian hair follicles go
through three (3) distinct growth
cycles.
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Anagen
Catagen
Telogen
GROWTH AND REPLACEMENT OF
HAIR
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Anagen:
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The active growth phase;
human head hairs spend
about two to four months in
this phase; 80% to 90% of
the hairs are in this growth
cycle.
GROWTH AND REPLACEMENT OF
HAIR
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Catagen:
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The breakdown phase; lasts
two to four weeks, 2% of the
hairs are in this phase.
GROWTH AND REPLACEMENT OF
HAIR
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Telogen:
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The resting phase; lasts two to
four months, until they fall out
naturally or are forcibly
removed, about 10% to 18% of
the hairs are in this phase.
IDENTIFICATION OF HUMAN HAIR
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The first step of forensic identification
and comparison of hairs begins with
whole mount light microscopy.
 The hair(s) in question must be
identified as to species, race and body
(somatic) origin.
 Human hairs can be readily
distinguished from animal hairs in
several ways, mainly by examining the
cuticles and medullae.
IDENTIFICATION OF HUMAN HAIR
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Racial Origin:
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Caucasian - Indo European
 Shaft diameter: moderate with
minimal variation (mean
diameter for human head hairs
- 80um)
 Pigment granules: sparse to
moderately dense with fairly
even distribution
 Cross-sectional shape: oval
IDENTIFICATION OF HUMAN HAIR
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Racial Origin:
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Negroid – African
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􀁺 Shaft diameter: moderate to
fine with considerable variation
 􀁺 Pigment granules: densely
distributed (hair shaft may be
opaque) and arranged in
prominent clumps
 􀁺 Shaft: prominent twist and curl
 􀁺 Cross-sectional shape:
flattened
IDENTIFICATION OF HUMAN HAIR
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Racial Origin
 Mongoloid - Eastern Asian,
Eskimo-Aleutian, and Native
American
Shaft diameter: coarse and
usually with little or no variation
 Pigment granules: densely
distributed and often arranged in
large patchy
 areas or streaks
 Medulla: prominent (often broad
and continuous)
 Cuticle: thick
 Cross-sectional shape: round
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IDENTIFICATION OF HUMAN HAIR
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Somatic Origin:
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Head
 Long with moderate shaft diameter and
diameter variation
 Medulla absent to continuous and relatively
narrow when compared to the structure of
hairs from other body areas
 Often with cut or split tips
 Can show artificial treatment, solar
bleaching, or mechanical damage
 Soft texture, pliable
IDENTIFICATION OF HUMAN HAIR
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Somatic Origin:
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Pubic
Shaft diameter coarse with wide
variations and buckling
 Medulla relatively broad and usually
continuous when present
 Root frequently with tag
 Tip usually tapered, rounded, or
abraded
 Stiff texture, wiry
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IDENTIFICATION OF HUMAN HAIR
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Somatic Origin:
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Limb hairs (arm or leg)
 Diameter fine with little variation
 Gross appearance of hair is arc-like in
shape
 Medulla is discontinuous to trace with a
granular appearance
 Tips usually tapered often blunt and
abraded, rounded scale ends due to
wear
 Soft texture
IDENTIFICATION OF HUMAN HAIR
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Somatic Origin
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Beard or Mustache hairs
Diameter very coarse with
irregular or triangular crosssectional shape
 Medulla very broad and
continuous, may be doubled
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IDENTIFICATION OF HUMAN HAIR
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Somatic Origin
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Chest hairs
Shaft diameter moderate and variable
 Tip often darker in color, long and fine, arc-like
 Medulla may be granular
 Stiff texture
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IDENTIFICATION OF HUMAN HAIR
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Somatic Origin
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Underarm hairs
Resemble pubic hairs in general appearance,
but less wiry
 Medullary appearance similar to limb hairs
 Diameter moderate and variable with less
buckling than pubic hairs
 Tips long and fine, frequently with bleached
appearance
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IDENTIFICATION OF HUMAN HAIR
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Somatic Origin:
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Other
Eyebrow: Stubby, some diameter fluctuation,
saber-like in appearance
 Eyelash: Short, stubby with little shaft diameter
fluctuation, saber-like in appearance
 Trunk: A combination of features of limb and
pubic hairs, a transitional hair
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IDENTIFICATION OF HUMAN HAIR
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As a rule, most forensic
comparisons are conducted using
scalp or pubic hairs. Body and limb
hairs are generally considered
unsuitable for comparison
purposes.
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Artificial Treatment:
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Bleached
Dyed
EXAMPLES OF RACIAL HAIR
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Caucasian:
EXAMPLES OF RACIAL HAIR
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Negroid
EXAMPLES OF RACIAL HAIR
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Mongoloid
VARIATIONS IN COLOR
COLLECTION AND EXAMINATION
OF HAIR
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Always photograph the item and note its location first
before collecting it.
Always be sensitive to cross-contamination issues.
Always wear gloves to collect evidence.
Always use clean, unused paper bindles or containers.
Use fingers or tweezers to collect crime scene evidence.
Collect good representative exemplary (known) hairs from the
scalp and/or pubic region.
Collect exemplars from both the victim and suspect.
Always maintain the chain of custody.
CONCLUSION AND REPORT
WRITING
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Forensic laboratory reports of hair comparisons
normally will provide one of three answers:
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The hairs matched in microscopic characteristics,
indicating an association.
The hairs are not alike and therefore did not come
from the same person.
No conclusion can be drawn from the evidence.
This may be due to insufficient specimen, racial
mixtures, or unsuitable exemplars.
CONCLUSION
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Types of hairs
Hair structure and growth
Race and body origin
Evidence collection procedures
Microscopy and results
REFERENCES
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Saferstein, R., Forensic Science Handbook, 1992 Prentice - Hall, Inc., Englewood
Cliffs, N.J., pp. 185-212.
Deadman, H.A., Human Hair Comparison Based on Microscopic Characteristics,
Proceedings of the International Symposium on Forensic Hair Comparisons,
(Washington, D.C.: Government Printing Office, 1985), pp.. 45-49.
Linch, Charles A., et. Al, Evaluation of the Human Hair Root for DNA Typing
subsequent to Microscopic Comparison, JFS 1998; 43 (2), pp.. 305-314.
Bisbing, R.E., The Forensic Identification and Association of Human Hair, Forensic
Science Handbook, Saferstein, R. ed. Englewood Clifffs, N.J., Prentice-Hall, Inc.,
1982, pp.. 209-272.
Gaudette, B.D., An Attempt at Determining Probabilities in Human Scalp Hair
Comparison, JFS., 1973, pp.. 599-605.
FBI, Microscopy of Hairs, A Practical Guide and Manual, Issue #2, 1977,
Washington, D.C., pp.. 1-24.