BCCE 30 July 2012 State College, PA

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

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

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”

GROWTH OF HAIRS cont’d

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

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

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

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

MICROANATOMY cont’d

• Examples of scale patterns

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

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

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

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

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

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

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

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

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

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

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:

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

DNA AND HAIRS

• mtDNA offers a way to add information to microscopic hair examinations

• Microscopic and molecular analyses are complementary techniques

SUMMARY

• Hairs are among the most often collected and potentially useful types of trace evidence

• Microscopical comparisons and mitochondrial _____ yield information