BCCE 30 July 2012 State College, PA
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Transcript of BCCE 30 July 2012 State College, PA
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BCCE30 July 2012
State College, PA
Forensic Hair Examination Jay A. Siegel, Ph.D. – Professor, Forensic Science
Gina Ammerman, M.S. – Lecturer, Forensic Science
Forensic and Investigative Sciences Program
Indiana University Purdue University Indianapolis
Indianapolis, IN
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INTRODUCTION • Hairs make good ________
_______because they can survive for many _______, carry __________ information, and are easy and cost-effective to examine.
• _______can also be extracted from hairs
• Hairs offer _____ investigative and adjudicative information
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GROWTH OF HAIRS• Hairs are a structure only common to ________• Fibrous growths that originate from epidermis
– _________ is structure within which hairs grow• Roughly cylindrical tube with a larger pit at the bottom• Hair is soft at base and hardens and dries out as it
proceeds up the follicle– Hair is made of ________
• Tough protein-based material from which hair, nails, and horns are made
• Hardening process is called keratinization– Hair is “dead” when it reaches our skin
– Follicle contains ________ vessels, nerves and sebaceous glands, which produce ____ that coat hairs keeping them soft and pliable
– ______ have muscles called pili arrector that raise hairs causing “goose bumps”
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GROWTH OF HAIRS cont’d
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GROWTH OF HAIRS cont’d
• Hairs have ______ phases of growth– Anagen is the actively ________ phase
• Follicle produces ___ _____and pushes them up the hair shaft as they become incorporated into the structure of the hair
• Cells in follicle produce ________ or pigment that impart color to hair
– Cells are called melanocytes
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GROWTH OF HAIRS cont’d– Hair transitions into a______phase called catagen
phase• Follicle begins to shut down production of cells, cells
shrink, and root condenses into a bulb-shaped structure called a root bulb or club root
– Telogen phase is the resting phase for the follicle• Cell production has ceased completely, root condenses
into a bulb and it is held in place by mechanical connection at the base of the root
• When connection
breaks, follicle is
triggered back into
_______phase
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MICROANATOMY• On macroscopic scale, hair has a root,
shaft and tip– _____ is the portion that formerly was in
follicle; proximal portion of hair– ______ is the main portion of the hair– ___ is the distal most portion of the hair
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MICROANATOMY cont’d• Microanatomy of hair includes
cuticle, cortex, and medulla– ________ of hair is a series of
overlapping layers of scales that form a protective coating
• Animal hairs have scale patterns that differ by species
• Humans have scale pattern called imbricate
– _______ makes up bulk of the hair; consists of spindle-shaped cells that contain or constrain numerous structures
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MICROANATOMY cont’d
• Examples of scale patterns
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MICROANATOMY cont’d• Spindle-shaped cells are sometimes called
fusiform• ________granules are found in cortex and are
dispersed variably throughout the cortex– Vary in size, shape, aggregation and distribution
• Small bubbles called cortical fusi may appear in cortex
– May be sparse, aggregated or evenly distributed
• Ovoid bodies, which look like large pigment granules, may appear irregularly in cortex• Cortical or medullary __________, which appear as small explosion in middle of hair, may be found
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HUMAN vs. NON-HUMAN HAIRS
• Relatively _____ to determine if hair is human or non-human
• Determining what kind of non-human hair may be more difficult
• ______ hairs have several macroscopic characteristics that distinguish them from human hairs
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HUMAN vs. NON-HUMAN HAIRS cont’d
– Guard hairs are large stiff hairs that make up the outer part of the animal’s coat• Used for microscopic identification• Guard hairs may have a widening in the upper
half of the shaft called a shield• A subshield stricture may be found below the
shield– A narrowing of the hair to slightly less than the
normal, non-shield shaft diameter– May be accompanied by bend in shaft at stricture
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HUMAN vs. NON-HUMAN HAIRS cont’d– Thinner, softer fur hairs fill in the rest of the coat,
providing warmth and bulk• Not useful for microscopic identification
– Animals have vibrissa, which are whiskers or the long, stiff often white hairs around the snout and muzzle
– Some non-human hairs are color banded or show abrupt color transitions
– Scale patterns may be useful in identifying animal hairs
• Use scanning electron microscope or make a scale cast and view with light microscope
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BODY AREA DETERMINATION • Humans have a wide variety of hairs on their
bodies– Characteristics of these hairs may allow for an
estimation of body area origin• Head, pubic, facial, chest, axillary, eyelash/eyebrow,
and limb• Typically, only head and pubic hairs are suitable for
microscopic comparison
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BODY AREA DETERMINATION cont’d
• Hairs not fitting into one of these categories may be called transitional body hairs
• Buckling is an abrupt change in direction of the hair shaft with or without a slight twist
• Shouldering is an asymmetrical cross-section of hairs
– Determination of body area origin may be difficult or impossible
• Labeling hair as “body hair” may be sufficient
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ANCESTRAL ESTIMATION• ________ or ancestry of an individual
from his or her hair can be estimated
• Morphology and color of hair can give an indication of a person’s ancestry– Three main ancestral groups are used:
Europeans, Africans, and Asians– Head and pubic hairs provide the clearest
evidence for ancestral estimates– Some examiners also categorize
populations as mixed race or other
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DAMAGE, DISEASE, AND TREATMENTS
• _______ may cut, dye, braid, shave, etc. their hair– Tips of hair provide good
information about treatment of hair
• Angle, clean straight border, long curved “tail,” blackened and bubbled or expanded, crushed
– Bleaching removes pigmentation
– Coloring may be added to hair
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DAMAGE, DISEASE, AND TREATMENTS cont’d
• Some ________ affect hair or follicles and are distinctive– Pili annulati refers to hairs with colored
rings– Monilethrix makes hairs look like a string of
beads– Pili torti is a twisting of the hair along its
length
• ________ on hair should be noted• _____ and sex cannot be determined
from looking at hairs
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COMPARISON OF HUMAN HAIRS
• Goal of most forensic hair examinations is the comparison of a questioned hair or hairs from a crime scene to a known hair sample– Known hair sample
consists of 50-100 hairs from all portions of area of interest
– Comparison microscope is used for examination
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COMPARISON OF HUMAN HAIRS cont’d– Examined from root to tip, at magnifications of
4x to 250x– Three basic conclusions can be drawn from a
forensic hair comparison:
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COMPARISON OF HUMAN HAIRS cont’d
• The questioned hair could have come from the same person who provided the known sample
– Not a positive form of identification
• No conclusion can be drawn as to whether the questioned hair could have come from the known source
• The questioned hair did not come from the known source
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DNA AND HAIRS
• mtDNA offers a way to add information to microscopic hair examinations
• Microscopic and molecular analyses are complementary techniques
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SUMMARY
• Hairs are among the most often collected and potentially useful types of trace evidence
• Microscopical comparisons and mitochondrial _____ yield information