Transcript File - CHS Forensics

Hair
CHS
Forensics
Mr. McNiff
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Hair
Glossary
Introduction
Basic Structure of Hair
Hair Identification: Animal Versus
Human Hairs
Human Hair Classifications
Methods of Hair Recovery
Human Hairs Identification
Comparison Characteristics
Conclusions
Glossary
• Achromat: An objective lens system
constructed of glass with limited
quality of correction for color and
spherical
aberration.
Glossary
• Anagen:
Actively
growing root
stage.
Glossary
• Catagen: A
transitional
root stage between
the actively
growing anagen
stage and the
resting telogen
stage.
Glossary
• Comparison microscope: Two microscopes
joined by an optical bridge with a split
screen to see both fields of views at the
same time.
• Cortex: Middle portion of hair extending
from the cuticle to the medulla and
containing the pigment granules, cortical
fusi, and ovoid bodies.
• Cortical fusi: Air spaces located in the
cortex of hairs.
Glossary
• Cuticle: Translucent outer layer of the
hair shaft consisting of overlapping
scales.
• Fluorite system: An objective system
constructed of fluorspar that provides
improved color and spherical correction
over achromatic lens systems.
• Fur hairs: Fine hairs that make up the
undercoat of mammals and provide
warmth.
Glossary
• Guard hairs: Coarse hairs that
provide protection and are usually
longer than fur hairs.
• Keratin: A fibrous protein forming the
chemical basis for hair, nails, and
feathers.
• Medulla: The central portion of hair,
the core area.
• Melanin: A pigment that gives hair its
color.
Glossary
• Miscible: Able to be mixed together.
• Oil immersion: A system that uses oils
of a known refractive index to test
the refractive index of other
materials and provide greater
resolution than air-mounted
specimens.
Glossary
• Ovoid bodies: Dark bodies of
unknown origin that are a useful
discriminatory characteristic in their
pattern of appearance.
• Papilla:
Connective tissue from which hair is
generated from the follicle.
Glossary
• Pigment granules: Melanin granules
whose size, shape, density, and
distribution vary.
• Refractive index: The ratio of the
velocity of light in air to the velocity
of light in a medium.
• Resolving power: The ability of the
microscope to make visible the
individual parts of an image
Glossary
• Scales: Outermost portion of the
cuticle, flattened and imbricate in
humans, pointing toward the distal
end of the hair shaft.
• Tactile hairs (Vibrissae): Whiskers
only found on animals.
Glossary
• Telogen: Resting
stage when the
root takes on club
shape and is
ready to be
naturally shed.
• Vellus: Fine body
hair.
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Hair
Glossary
Introduction
Basic Structure of Hair
Hair Identification
Animal Versus Human Hairs
Human Hair Classifications
Methods of Hair Recovery
Human Hairs Identification
Comparison Characteristics
Conclusions
Hair Evidence
• Each species of animal possesses
hair with characteristic that
distinguish one animal from another.
–length
–Color
–Shape
–Root appearance
–Internal microscopic features
Introduction
• One of the most common types of
physical evidence in a criminal
investigation is hair evidence.
• The identification and comparison of
human and animal hairs can be
helpful in demonstrating physical
contact with a suspect, victim, and
crime scene.
Introduction
• Hairs can provide investigators with
valuable information for potential
leads.
• The first step necessary in the
analytical process is the identification
and comparison of human and animal
hairs.
Introduction
• Microscopy of Hairs: A Practical
Guide and Manual by John W. Hicks
is intended to introduce hair
evidence to the forensic examiner
and to provide a foundation for its
proper identification and comparison.
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Hair
Glossary
Introduction
Basic Structure of Hair
Hair Identification
Animal Versus Human Hairs
Human Hair Classifications
Methods of Hair Recovery
Human Hairs Identification
Comparison Characteristics
Conclusions
Basic Structure of Hair
• A hair can be defined as a slender,
thread-like outgrowth from a follicle
in the skin of mammals.
• Composed mainly of keratin, it has
three morphological regions—the
cuticle, medulla, and cortex.
1. Hair Diagram
Basic Structure of Hair
• A hair grows from the papilla and
with the exception of that point of
generation is made up of dead,
cornified cells.
• It consists of a shaft that projects
above the skin, and a root that is
imbedded in the skin
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Hair
Glossary
Introduction
Basic Structure of Hair
Hair Identification
Animal Versus Human Hairs
Human Hair Classifications
Methods of Hair Recovery
Human Hairs Identification
Comparison Characteristics
Conclusions
Hair Identification
Animal Versus Human Hairs
• Human hairs are distinguishable from
hairs of other mammals. Animal hairs
are classified into the following three
basic types.
–Guard hairs that form the outer
coat of an animal and provide
protection
–Fur or wool hairs that form the
inner coat of an animal and provide
insulation
Hair Identification
Animal Versus Human Hairs
–Tactile hairs (whiskers) that are
found on the head of animals
provide sensory functions
Hair Identification
Animal Versus Human Hairs
• The medulla, when present in human
hairs, is amorphous in appearance,
and the width is generally less than
one-third the overall diameter of
the hair shaft.
• The medulla in animal hairs is
normally continuous and structured
and generally occupies an area of
greater than one-third the overall
diameter of the hair shaft.
Hair Identification
Animal Versus Human Hairs
• The root of human hairs is commonly
club-shaped, whereas the roots of
animal hairs are highly variable.
Human Hairs
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Horse Hair
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Dog Hair
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Cat Hair
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Mouse Hair
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Rabbit Hair
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Deer Hair
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Cow Hair
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Pig Hair
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Hair
Glossary
Introduction
Basic Structure of Hair
Hair Identification
Animal Versus Human Hairs
Human Hair Classifications
Methods of Hair Recovery
Human Hairs Identification
Comparison Characteristics
Conclusions
Human Hair Classifications
• Hair evidence examined under a
microscope provides investigators
with valuable information.
• Hairs found on a knife or club may
support a murder and/or assault
weapon claim.
Human Hair Classifications
• A questioned hair specimen can be
compared microscopically with hairs
from a known individual, when the
characteristics are compared sideby-side.
Hair sample
at left
from
victim's
vehicle and
suspect's
hair at
right
Human Hair Classifications
• Human hairs can be classified by
racial origin:
–Caucasian (European origin),
–Negroid (African origin),
–Mongoloid (Asian origin).
• In some instances, the racial
characteristics exhibited are not
clearly defined, indicating the hair
may be of mixed-racial origin.
Human Hair Classifications
• The region of the body where a hair
originated can be determined with
considerable accuracy by its gross
appearance and microscopic
characteristics.
Human Hair Classifications
• The length and color can be
determined.
• It can also be determined whether
the hair was forcibly removed,
damaged by burning or crushing, or
artificially treated by dyeing or
bleaching.
Fallen Out Hairs
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Natural Tip
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Pulled Out-By the Root
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Broken-Torn
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Cut Hair
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Dyed hair
Cut with razor
Worn Razor cut
Glass-Cut or Broken Hair Tip
Abraded Hair Tip
Burned Hair
Lice Egg
Postmortem Root Band
Human Hair Classifications
• The characteristics and their
variations allow an experienced
examiner to distinguish between hairs
from different individuals.
• Hair examinations and comparisons,
with the aid of a comparison
microscope, can be valuable in an
investigation of a crime.
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Hair
Glossary
Introduction
Basic Structure of Hair
Hair Identification
Animal Versus Human Hairs
Human Hair Classifications
Methods of Hair Recovery
Human Hairs Identification
Comparison Characteristics
Conclusions
Methods of Hair Recovery
• Sir Edmund Locard's principle (1930)
states that "whenever two objects
come into contact, a transfer of
material will occur. Trace evidence
that is transferred can be used to
associate objects, individuals, or
locations“
Methods of Hair Recovery
• Because of the nature of trace
evidence, when processing evidentiary
items, care should be taken to
minimize the possibility of
contamination and cross-transfer.
• Examinations should be sequenced to
maximize the potential value of the
submitted evidence.
Methods of Hair Recovery
• Hairs can be recovered from
evidentiary items using a number of
different techniques.
• Some of the methods used to collect
hairs from clothing and bedding items
are scraping, shaking, taping, and
picking.
Methods of Hair Recovery
• Debris from large carpeted surfaces
might be vacuumed into a filtered
canister.
• If the specific location of a hair on
a clothing item is important, it might
be necessary to pick off the hair or
tape the item and record where the
hair was removed.
Methods of Hair Recovery
• Whichever method is used, it should
be done in a location designed for
that purpose to avoid the possibility
of contamination and cross-transfer.
• Special lighting and magnification may
facilitate the location and recovery.
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Hair
Glossary
Introduction
Basic Structure of Hair
Hair Identification
Animal Versus Human Hairs
Human Hair Classifications
Methods of Hair Recovery
Human Hairs Identification
Comparison Characteristics
Conclusions
Human Hairs Identification
• Key characteristics serve as racial
indicators. These indicators are
generalities and apply primarily to
head hairs.
• The examiner may encounter hairs
that cannot easily be associated with
a particular racial model because of
poorly defined characteristics,
limited size, or inconsistent
indicators.
Human Hairs Identification
• These hairs can be identified as
apparent racial mixtures or as not
classifiable.
• In spite of an inability to
substantiate race, the hair may still
be of value for comparison purposes.
Human Hairs Identification
• This racial mixture may serve to
further individualize the hair and its
source, particularly if the same
mixed racial characteristics are
observed in both the questioned and
known samples.
Human Hairs Identification
• Caucasian
–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
Photomicrograph of Cross-section of
Caucasian Hair
Photomicrograph of Caucasian Head
Hair
Human Hairs Identification
• Negroid
–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
Cross-section of African originHair
African Origin Head Hair
Human Hairs Identification
• Mongoloid
–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
Cross-section of Asian Origin Hair
Asian Origin Head Hair
Caucasian Head Hair
African origin Head Hair
Human Hairs Identification
• Head Hairs
– 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
Human Hairs Identification
• Pubic Hairs
–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
Human Hairs Identification
• Limb Hairs
–Diameter fine with little variation
–Gross appearance of hair is arclike 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
Human Hairs Identification
• Facial Hairs (Beard/Mustache)
–Diameter very coarse with irregular
or triangular cross-sectional shape
–Medulla very
broad and
continuous,
may be
doubled
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Hair
Glossary
Introduction
Basic Structure of Hair
Hair Identification
Animal Versus Human Hairs
Human Hair Classifications
Methods of Hair Recovery
Human Hairs Identification
Comparison Characteristics
Conclusions
Comparison Characteristics
• Certain physical features such as
sex, size, age, shape, eye color, hair
texture, and color can distinguish
individuals.
• None of these features is peculiar to
only one individual, but the general
appearance and arrangement of these
features serves as criteria for
identification.
Comparison Characteristics
• There are, likewise, a number of
features or characteristics that may
be present in a given hair sample
that, when considered collectively,
provide a basis for association
Comparison Characteristics
• The process of identification or
association involves distinct stages in
the course of an examination.
• The following 15 different features
or characteristics should be
considered in the comparison of hair
specimens.
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Hair
Glossary
Introduction
Basic Structure of Hair
Hair Identification
Animal Versus Human Hairs
Human Hair Classifications
Methods of Hair Recovery
Human Hairs Identification
Comparison Characteristics
Conclusions
Conclusions
• There are three basic conclusions
that can be reached from a
microscopic examination and
comparison of hairs.
–The hairs from the questioned (Q)
source exhibit the same
microscopic characteristics as the
hairs in a known (K) hair sample
and can be associated to the
source of the known hairs.
Conclusions
–The hairs from the questioned
source are microscopically
dissimilar to the hairs in a known
hair sample and cannot be
associated with the source of the
known hairs.
Conclusions
–The questioned hairs exhibit both
similarities and slight differences
to hairs found in a known hair
sample, and no conclusion can be
reached whether they could have
originated from the known source.
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Pictures
http://www.wildwestroundup.com/associates.html
http://www.gabelwire.com/2009/12/23/artistic-leaps-in-forensics/
http://keratinhairtreatmentdirect.com/keratin-hair-straightening/
http://www.telegraph.co.uk/news/picturegalleries/theweekinpictures/473638
4/The-week-in-pictures-20-February-2009.html?image=5
http://www.etsy.com/listing/38169952/barbie-doll-blonde-curly-jointed
http://www2.fbi.gov/hq/lab/fsc/backissu/jan2004/research/2004_01_resea
rch01b.htm
http://hannahc12.wordpress.com/category/forensic-science/
http://wikipedia.org
http://eternalbeautymedicalclinic.com
http:// frostydrew.org
http:// swiftcraftymonkey.blogspot.com
http:// swgmat.org
http:// iukk.blogspot.com
http:// ouhsc.edu
http:// laszlokadar.com
http:// villageofjoy.com
http:// pets.webmd.com
http://histology-world.com
Pictures
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http://www.kcmo.org/police/AboutUs/Departments/Investigations/RegionalCr
imeLab/Sections/TraceEvidance/index.htmhttp://
http://www.celticnz.co.nz
http://www.bsapp.com
http://www.stores.crimetech.net
http://www.snailtail.com
http://www2.fbi.gov/hq/lab/fsc/backissu/jan2004/research/2004_01_resea
rch01b.h
http://www.bsapp.com/forensics_illustrated/pppresentations.htm tm
http://www2.fbi.gov/hq/lab/fsc/backissu/july2000/deedric1.htm#Hair
Anatomy and Growth
Reference
USA. Federal Bureau of Investigation. Trace Evidence Unit. Hairs, Fibers,
Crime, and Evidence. By Douglas W. Deedrick. US Dept Justice, 2000.
Web. 18 Aug. 2011.
<http://www2.fbi.gov/hq/lab/fsc/backissu/july2000/deedric1.htm#Hair
Anatomy and Growth>.
Deedrick, Douglas W. "Deedrick - Forensic Science Communications January 2004." FBI — Federal Bureau of Investigation. FBI — Federal
Bureau of Investigation, Nov. 2004. Web. 23 Aug. 2011.
<http://www2.fbi.gov/hq/lab/fsc/backissu/jan2004/research/2004_01_re
search01b.htm>.
Sapp, Brennon. Species & Conditions of Hair. Forensics Illistrated Step
under the Tape. Brennon Sapp, 4 May 2003. Web. 23 Aug. 2011.
<http://www.bsapp.com/forensics_illustrated/pppresentations.htm>.
Easybib used for citation