hair chs forensics mr. mcniff. hair glossary introduction basic structure of hair hair...

HairCHS

ForensicsMr. McNiff

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.

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.

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

Cuticle

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 IdentificationAnimal 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 IdentificationAnimal Versus Human Hairs

–Tactile hairs (whiskers) that are found on the head of animals provide sensory functions

Hair IdentificationAnimal 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 IdentificationAnimal 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 side-by-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

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.

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.

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 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

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

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.

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.

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/4736384/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_research01b.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• http://www.kcmo.org/police/AboutUs/Departments/

Investigations/RegionalCrimeLab/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_research01b.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_research01b.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>.

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