footwear impression evidence：鞋类印象证据

CrimeScenePhotographyFOOTWEARANDTIRE

IMPRESSIONEVIDENCEFOOTWEARANDTIRE

IMPRESSIONEVIDENCEByProfessorBobWarnockandJerryDambrogioFOOTWEAREVIDENCEDIRECTPHYSICALCONTACTTRANSFEROFCLASSANDORINDIVIDUALCHARACTERISTICSIMPRESSIONEVIDENCE“objectsormaterialsthathaveretainedthecharacteristicsofotherobjectsormaterialsthroughphysicalcontact”Personscommittingacrimeleavefootwearimpressionsenrouteto,atandexitingfromthecrimescene.THREE-DEMENSIONALIMPRESSIONSArethosethathavesignificantdepth,inadditiontolengthandwidth.Thesearenormallyfoundin:SoilSandSnowTHREE-DEMENSIONALIMPRESSIONSTHREE-DEMENSIONALIMPRESSIONSPhotographCastTWO-DEMENSIONALIMPRESSIONSPhotographCollectsubstrateifPossibleIfnotrecoverwithappropriatetechniqueThree-DimensionalImpressionPhotographDocumentCastColdWeatherCastingPartialmeltingoftheoriginaldetailsduetheheatgeneratedbythesettingofthecastingmaterial.Anothercommonproblemisthefreezingofthecastingmaterialbeforethecasthasset.ColdWeatherCastingGrayAutoPrimerSnowWaxAdditionofsnowtothecastingmaterialduringmixing.PotassiumSulfateTWO–DEMENSIONALIMPRESSIONSPositiveimpressionAnimpressionthatresultswhenashoedepositsmaterialontoasubstrate.Theresiduevisuallyrepresentstheareasofthesolethatactuallycameincontactwiththesurface.TWO–DEMENSIONALIMPRESSIONSNegativeimpressionIsproducedwhenthecontactareaoftheshoeremoveresiduefromasurfaceandinwhichtheresidueonthesurfaceremainswheretheareasofsoledidnotcomeincontactwiththesurface.Negativeimpressionsoccurlessfrequentlythenpositiveimpressions.TWO–DEMENSIONALIMPRESSIONSDryoriginresidueimpression.Whenshoestrackacrossadirtysurface,thebottomofthesoleswillaccumulateacoatingofresidue.Iftheythentrackontoarelativelycleansurface,thesameresiduewillbedepositedintheformoffootwearimpressions.TWO–DEMENSIONALIMPRESSIONSWetoriginimpressionImpressionsmadewhenacleanshoesoleiswetordamporthereceivingsurfaceiswetordamp.Thistypeofimpressionmaybeenhancedwithfingerprintpowder.TWO-DEMENSIONALPhotography–ObliqueLightingRecoverSubstrateLiftImpressionGel-LiftElectrostaticLifterCarbonPaperElectrostaticLifterTheelectrostaticallychargedliftingfilmisdrawndowntothesurface,andthedustparticlesintheimpressionareattractedtotheliftingfilm.Theconstructionofthefilmallowsittostoretheelectrostaticcharge,thusretainingthedustparticlesafterthechargehasbeendisconnected.ElectrostaticDustPrintLiftingDevicesUsedOn:PaperLinoleumSeatCoversWoodCarpetConcreteAsphaltDustImpressionsUsedondrydustimpressionsonly…..Thefilmwiththeimpressionisviewedwithobliquelighting.Dustimpressionshouldbephotographedpriortoattemptingtoliftthem.Gel-LiftingGellifterscontainathick,non-aggressive,low-adhesivegelatinlayerthatpermitstheliftingoftracesfromalmosteverysurface.Viewunderobliquelighting.Photographimpressionbeforelifting.COMPARISONMETHODOLOGYSIDEBYSIDEOVERLAYSCOMPARISONMICROSCOPEAREASOFEXAMINATIONDESIGN(FULLORPARTIAL)ManufacturingCharacteristicsPhysicalShapeandSizeWearCharacteristicsIndividualIdentifyingCharacteristicsNomenclatureCLASSCHARACTETRISTICPHYSICALSIZESHAPEGENERALDESIGNManufacturingProcessesMoldedprocesses,wherethesoles,oncemolded,representtheirfinalsizeandshape.Cutprocesses,wheresolingmaterialinitiallymoldedorformed,isthencutortrimmedinsomewaybeforereachingafinalshapeandsize.MOLDINGPROCESSESCompression-MoldedOutsolesInjection–MoldedOutsolesOpen-PourMoldingMoldedProcessesCalenderingProcessingManyvariablesoccurduringthecalendaringoperationthatcontributetomakingtheoutsolematerial,andthereforetheresultingoutsolesextremelyindividual.CutProcessesPHYSICALSIZENOTASHOESIZEBUTTHEPHYSICALDIMENSIONSOFTHESOLEANDDESIGNPATTERN.ONEPERSON–MANYSHOESTYPESIZELENGTHWIDESTPARTNikeTennis8½279mm90mmNikeTennis8½285mm94mmNikeJogging8½290mm111mmBassSandals10M282mm90mmBostonianLoafers8½295mm109mmBostonianLoafers8½285mm98mmSperryDeckShoe8½286mm103mmWEAREXAMINATIONEFFECTOFFRICTIONANDABRASIVEFORCESONSOLESITISTHEPOSITIONANDDEGREEOFWEARTHATISRELEVANTGENERALWEARSamePair45DaysLaterSamePair90DaysLaterAreaofMajorChangesSCHALLAMACHPATTERNOccursonasoleasaresultofabrasivewear.Theabrasioncausestherubbertostretchandrollover.Theresultantridges(tendrils)createridgepatternssimilartothatofafingerprint.SCHALLAMACHPATTERNThepatternisuniqueandcanbeusedasthebasisforapositiveidentification.Thepatterncanchangecompletelyafterbetween6to16hoursofadditionalwear.Thepatternnormallyrunsperpendiculartotheaxisoftheshoe,primarilyinthetoeandheelarea.SCHALLAMACHPATTERNCOMBINEDCLASSCHARACTERISTICSCombinedclasscharacteristicscanrapidlyreducethenumberofshoessharingthosecharacteristics,thefollowinghypotheticalbutnotuncommonexampleisoffered.10,000pairsofsizetenbasketballshoesoutatotalorderof75,000shoesofsamedesignandbrandaremadeInordertomeetproductiondemandsfourpairsofsizetenmoldswereused.Eachhandgravedmoldiseasilydistinguishablefromeachother.Thisgivesyou2,500pairsfromeachmold.COMBINEDCLASSCHARACTERISTICS3.Ifyoumatchuponeleftfromamoldandonerightfromamolditreducesthetotalpossiblepairsdownto625pairs.4.Ifanothervariablecharacteristicsuchasatoecapwhichvariesinitspositionispartofthemanufacturingprocessandcanoccurinoneoftenwaysoneachoutsole,thechancesofaleftpairandrightshoefromthesamerespectiveleftandrightmoldandhavingtheotheridenticalvariablewouldbe6.25chancesoutof10,000RESULTSPositiveIdentificationNon-IdentificationProbablyMadePossibleMadePossibleDidNotMakeNon-ConclusivePOSITIVEIDENTIFICATIONItwasdeterminedthattheimpressionrepresentedbythecastwasmadebytherightshoesubmittedNON-IDENTIFICATIONItwasdeterminedthattheimpressionrepresentedbythecastwasnotmadebytherightshow.PROBABLYMADEItwasdeterminedthatthequestionedimpressioncorrespondsindesign,physicalsizeandshapeandgeneralconditionwiththeknownrightshoe.Inaddition,thecorrespondenceoftworandomindividualcharacteristicsindicateitishighlyprobablytheimpressionwasmadebytherightshoe.Itisveryunlikelythatanothershoeofthesamedesign,physicalsizeandshape,andgeneralconditionwouldalsosharetheaforementionedcharacteristics.POSSIBLYMADEItwasdeterminedthatthequestionedimpressioncorrespondsindesign,physicalsizeandshapeandgeneralconditionwiththeknownrightshoe.Duetothelimiteddetailretainedintheimpressionandlackofobservableindividualidentifyingcharacteristics,acloserassociationwasnotmadebetweentheimpressionandknownshoe.Thepossibilityexitsthatanotherrightshoe(s)ofthesamespecificdesign,physicalsize,andgeneralcondition,madethisimpression.POSSIBLEDIDNOTMAKESimilardesignfeaturesexistbetweenportionsofthequestionedimpressionandtheknownrightshoe;however,