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ForensicsPowerPointNotes Chapter6:Fibers

Whereverthesteps,whateverhetouches,whateverheleavesevenunconsciously,willserve

assilentwitnessagainsthim. Notonlyhisfingerprintsorhisfootprints,buthishair,thefibers

fromhisclothes,theglasshebreaks,thetoolmarksheleaves,thepainthescratches,theblood

orsemen

he

deposits

or

collectsall

of

these

and

more

bear

mute

witness

against

him.

This

is

evidencethatdoesnotforget.

PaulL.Kirk(19021970)Forensicscientist

FibersObjectives:

Howfiberscanbeusedascircumstantialevidencetolinkthevictim,suspect,andcrime

scene.

Whyfibersareclassevidence.

Whystatistics

are

important

in

determining

the

value

of

evidence.

FibersStudentsshouldbeableto:

Distinguishandidentifydifferenttypesoffibers.

Understandpolymerization.

Carryoutanexperimentinthinlayerchromatography.

Judgetheprobativevalueoffiberevidence.

Designand

carry

out

scientific

investigations.

Usetechnologyandmathematicstoimproveinvestigationsandcommunications.

Fibers Def:Anythreadlikeelementofmaterial.

Areconsideredclassevidence

Haveprobativevalue

Arecommontraceevidenceatacrimescene

Canbe

characterized

based

on

comparison

of

both

physical

and

chemical

properties

Fabric

Fabricismadeoffibers.

Fibersaremadeoftwistedfilaments

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Typesoffibersandfabric

Naturalanimal,vegetableorinorganicminerals.

Artificialmanufacturedorsynthesizedfromalterednaturalsources

Typesof

Fibers

Artificial(Synthetic)

Rayon

Nylon

Acetate

Acrylic

Spandex

Polyester

Natural

Silk

Cotton

Wool

Mohair

Cashmere

Angora

Classification Naturalfibersareclassifiedaccordingtotheirorigin:

Vegetableorcellulose

Ex:Cotton,rayon,celluloseacetate

Animalor

protein

Ex:Wool,silk,mohair,alpaca,angora

Mineral

Ex: Asbestos,fiberglass

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CelluloseFibers

Cottonvegetablefiber;strong,tough,flexible,moistureabsorbent,notshape

retentive

Rayonchemicallyalteredcellulose;soft,lustrous,versatile

Celluloseacetatecellulosechemicallyalteredtocreateanentirelynewcompound

notfoundinnature.

FiberComparison

Canyoutellthedifference(s)betweenthecottonontheleftandtherayonontheright?

ProteinFibers

Woolanimalfibercomingmostoftenfromsheep,butmaybegoat(mohair),rabbit

(angora),camel,

alpaca,

llama,

vicuna

Silkinsectfiberthatisspunbyasilkwormtomakeitscocoon;fiberreflectslightandhas

insulatingproperties

MineralFibers

Asbestosanaturalfiberthathasbeenusedinfireresistantsubstances

Rockwoolamanufacturedmineralfiber

Fiberglassamanufacturedinorganicfiber

Artificial(Synthetic)Fibers

(Madefromderivativesofpetroleum,

coalandnaturalgas)

Nylonmostdurableofmanmadefibers;extremelylightweight

Polyestermostwidelyusedmanmadefiber

Acrylicprovideswarmthfromalightweight,softandresilientfiber

Spandexextremeelasticproperties

FabricProduction

Textiles:Afabricwoveninadistinctivepattern

Fabricsarecomposedofindividualthreadsoryarns,madeoffibersthatareknitted,woven,

bonded,crocheted,felted,knottedorlaminated.

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Mostareeitherwovenorknitted.

Thedegreeofstretch,absorbency,waterrepellence,softnessanddurabilityareallindividual

qualitiesofthedifferentfabrics.

WeaveTerminology

Yarnacontinuousstrandoffibersorfilaments,eithertwistedornot

Warplengthwiseyarn

Weftcrosswiseyarn

Blendafabricmadeupoftwoormoredifferenttypesoffiber.

WeavePatterns

PlainWeave

SatinWeave

TwillWeave

PlainWeave

Thesimplestandmostcommonweavepattern

Thewarpandweftyarnspassundereachotheralternately

Designresemblesacheckerboard

TwillWeave

Thewarpyarnispassedoveronetothreeweftyarnsbeforegoingunderone

Makesadiagonalweavepattern

Designresemblesstairsteps

Denimisoneofthemostcommonexamples

SatinWeave

Theyarninterlacingisnotuniform

Createslongfloats

Interlacingweavepassesoverfourormoreyarns

Satinisthemostobviousexample

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TestingforIdentification

Densitymassofobjectdividedbythevolumeoftheobject

RefractiveIndexmeasuringthebendingoflightasitpassesfromairintoasolidorliquid

Fluorescenceusedfor

comparing

fibers

as

well

as

spotting

fibers

for

collection

Dyes

Componentsthatmakeupdyescanbeseparatedandmatchedtoanunknown.

Therearemorethan7000differentdyeformulations.

Chromatographyisusedtoseparatedyesforcomparativeanalysis.

Thewayafabricacceptsaparticulardyemayalsobeusedtoidentifyandcomparesamples.

FiberStains

Fiberstains(dyetechniques)canalsoprovideusinformationonmanufacturers

IdentificationandComparisonofFibers

FourierTransformInfraredanalysis(FTIR)basedonselectiveabsorptionofwavelengths

oflight

Opticalmicroscopyusespolarizinglightandcomparisonmicroscopes

Pyrolysisgaschromatographymassspectrometry(PGCMS)burnsasampleunder

controlledconditions,separatesandanalyzeseachcombustionproduct

CollectionofFiberEvidence

Bagclothingitemsindividuallyinpaperbags.

Makesurethatdifferentitemsarenotplacedonthesamesurfacebeforebeing

bagged.

Maketapeliftsofexposedskinareasofbodiesandanyinanimateobjects

Removedfibers

should

be

folded

into

asmall

sheet

of

paper

and

stored

in

apaper

bag.

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FiberEvidence

Fiberevidenceincourtcasescanbeusedtoconnectthesuspecttothevictimortothecrimescene.

InthecaseofWayneWilliams,fibersweighedheavilyontheoutcomeofthecase.Williamswas

convictedin1982basedoncarpetfibersthatwerefoundinhishome,carandonseveralmurder

victims.

DNATestsSoughtinGa.ChildKillings

TheAssociatedPress

Wednesday,November29,2006;12:54PM

ATLANTA LawyersforWayneWilliams,blamedforthemurdersoftwodozenchildrenandyoungmen

inthelate1970sandearly'80s,haveaskedtoperformDNAtestingondoghair,humanhairandblood.

Amotion

seeking

the

testing

was

filed

Tuesday

in

Fulton

County

Superior

Court.

Lawyer

Jack

Martin

said

inMaythatthedefenseplannedtomaketherequest.

Between1979and1981,29blacks,mostofthemboys,werekilledintheAtlantaarea,spreadingfear

throughouttheregion.

Williamswasconvictedin1982ofmurderingNathanielCater,27,andJimmyRayPayne,21,and

sentencedtotwoconsecutivelifeterms.Afterward,officialsdeclaredWilliamsresponsiblefor22other

deaths,andthosecaseswereclosed.

Williams,who

is

black,

has

contended

he

was

framed.

He

has

maintained

that

officials

covered

up

evidenceofKuKluxKlaninvolvementinthekillingstoavoidaracewarinthecity,whichinvestigators

havedenied.

WitnessestestifiedduringhistrialthatWilliamswasseenwithsomeofthevictims,buthewas

convictedlargelyonfiberevidence.

Hisappealshavebeenrepeatedlyrebuffed.AfederaljudgelastmonthrejectedWilliams'requestto

reconsiderevidenceheclaimspointstoanothersuspect.

Inthe

filing

Tuesday,

Martin

asked

to

perform

DNA

tests

on

hair

recovered

from

the

clothing

of

Cater

andPaynetocompareitwithdoghairrecoveredfromWilliams'Germanshepherd,Sheba.Martinalso

askedtotestdoghairlinkingWilliamstomurdersthatprosecutorsusedtoestablishakillingpattern

duringthetrial,eventhoughhewasn'tchargedinthem.