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1、FORENSICSCIENCE TraceEvidence1IntroductionTraceEvidence--anysmallpiecesofmaterial,man-madeornaturallyoccurringMostcommonexamples:HairFiber2TestQuestionsforTraceEvidenceWhatisit?Isitman-madeornatural?Whatisitssource?Howcommonisit?Canitbeidentifiedtoasi
2、nglesource?3HairHumanhairisoneofthemostfrequentlyfoundpiecesofevidenceatthesceneofaviolentcrime.Itcanprovidealinkbetweenthecriminalandtheact.Fromhaironecandetermine:HumanoranimalRaceOriginMannerinwhichhairwasremovedTreatedhairDrugsingested4DNAThehairsh
3、aftcontainsabundantmitochondrialDNA--inheritedonlyfromourmothers.ItcanbetypedbycomparingrelativesifnoDNAfromthebodyisavailable.OnlytherootcontainsnuclearDNA.5HairMorphologyTheStudyofStructureandFormPartsofthehairShaft--partofthehairthatsticksoutofthesk
4、inRoot--liesbelowtheepidermisFollicle--structurefromwhichthehairgrows6HairGrowthTerminologyAnagen--hairthatisgrowingCatagen--hairatrestTelogen--hairthatisdyingLength--00.5mmperdayor1centimeterpermonth;approximatelyonehalfinchpermonth7HairCuticleMosaicP
5、ectinateImbricatePetalDiamondpetalChevronThecuticleistheoutermostlayerofhairwhichiscoveredwithscales.Scalesalsoalwayspointtowardthetipofthehair.Thesescalesdifferbetweenspeciesofanimalsandarenamesbasedontheirappearance.Someofthesescalesarevariationsofth
6、esameandinclude:8ScaleTypesMosaicChevron9ScaleTypes(cont)PectinateImbricate10ScaleTypes(cont)PetalDiamondPetal11HUMANSCALESInordertovisualizethescalespaintfingernailpolishonaslideplaceahaironthepolishliftoffthehairandobservethescaleimprintsWhatpatterni
7、sseeninthisslide?12HairCortexThecortexgivesthehairitsshape.Ithastwomajorcharacteristics:Melanin--pigmentgranulesthatgivehairitscolorCorticalfusi--airspaces,usuallyfoundneartherootbutmaybefoundthroughoutthehairshaft13Themedullaisthehaircorethatisnotalwa
8、yspresent.Themedullacomesindifferenttypesandpatterns.Types:ContinuousIntermittentorinterruptedFragmentedAbsent--notpresentHairMedulla14HairMedullaPatternsUniserialMultiserialVacuolatedLatticeAmorphous(withoutadistinctpattern)15HUMANMEDU
