Tire Impression and Tire Track Evidence · 2018. 8. 29. · The type of evidence the researchers...
Transcript of Tire Impression and Tire Track Evidence · 2018. 8. 29. · The type of evidence the researchers...
YOYOWhattypeofevidencearetheseresearcherslookingat?Namethekindsofofinformationthatisavailableinthistypeofevidence.
WhoisLeadFoot?
Thetypeofevidencetheresearchersarelookingataretiremarkimpressions.
Thereisanabundanceofinformationthatcanbetakenfromatireimpression.Itisclassevidence,butwiththewearandspecificuseitcanbeindividualevidence.Thereismanufacturemakeandmodel,treaddesign,treadwear,materials,inflation,damagemarks,etc……
“LeadFoot”isaplayonwordsoftheconceptofBigFoot,alegendaryhuman-likecreaturethatissaidtoinhabitthedeepforestsandremoteplacesofthecountry.
IntrotoForensics:Ms.Scanlon,Ms.Mammolito1/2/2018
HappyNewYear!
Aim:Whyaretiremarkimpressionsimportantevidenceatacrimescene?
TireImpressionandTireTrackEvidence
I.Overview:
• Whatisatireimpression?=2or3-Dmarksthatreflectthetreaddesignanddimensionalfeaturesoftires
• Whatisatiretrack?=therelativedimensionsbetweentwoormoretiresofavehicle
http://www.suite101.com/view_image.cfm/454216
http://www.tire-information-world.com/image-files/tire-tracks-in-snow.jpg
CrimeScenesandTireTracks
• Whydowecareaboutthistypeofevidence?Tohelpproveasuspectvehiclewaspresentatthecrimesceneandtoreconstructevents/leadtootherevidence
II.Backgroundinfoontires• Tirescomeinthousandsofdesignsandnumeroussizes.
• Tiresonnewvehiclesareknownasoriginalequipment(OE)tires.
Importance=thesamemakeandmodelvehicleswillhavethesametiresizeandbrand
• Tirespurchasedtoreplaceworndownordamagedtiresarecalledreplacementtires.
Importance=replacementtiresareusuallynot thesamedesignasOE...soavehiclewith3or4replacementtires,eachofdifferentdesign,setsupauniquesituation
• Tireconstruction:• Tiresaremadeofvariouscompoundsofrubber,steel,andfabric.
• Thetireisconstructedwithoutanydesignfirst(greentire).Thenplacedinamoldwheretreadandsidewalldesignsareadded.
http://images.motorcyclecruiser.com/tech/tirez-cutaway-md.jpg
Greentire
http://www.sincerelysustainable.com/wp-content/uploads/2009/07/espec.jpg
III.Tiretreadandsidewallcomponents:
• Treaddesigncomponents—canbeassociatedwithabrandnameandmanufacturer• Sketchfigure19.3intextbookonpage379.
Besuretoindicatethefollowingpoints:centerline,rib,groove,slot,designelement,sipe,andtreadwearindicator
http://www.centralia.edu/academics/forensicscience/FORS%20101/PowerPointPres/LTire.ppt
• Sidewallcomponents—Ølabelside(faceoutward)Øserialside(faceinward)Informationimportanttoinvestigators• Tirebrandandstylename(bothsides)
• Ex.MichelinXM+S244
• Tiresize(bothsides)• Ex.P19575/R15
• DepartmentofTransportation(DOT)Number(serialside)• BeginswithDOT• Next=symbolsformanufacturerandplantcode(wheremade)• Next=3or4numbersthatrepresentweekandyeartiremanufactured(ex.4901=49th weekof2001)
• NOTE:sometiresareretread.ThesetireswillhaveaDOTRnumber.
http://images.motorcyclecruiser.com/tech/tirez-cutaway-md.jpg
IV.NoiseTreatment• Astiresrotatethedesignelementsvibrateandproducenoise.
• Ifallelementswerethesamesize(whichrelatestopitch),thenoisewouldbeveryloud.
• Noisetreatment=tireindustrycreatingtiredesignsthatvarythesizeofthedesignelementsaroundthetire.
Images:http://www.centralia.edu/academics/forensicscience/FORS%20101/PowerPointPres/LTire.ppt
V.Treadwearindicators:• Wearbars—indicatewhentireshouldbereplaced
Importanceinforensics=canberetainedin3-Dimpressions
Image:http://gallery.rennlist.com/albums/HRE-843-Yok-AVS/tire_wear_bar_front_1.jpg
VI.TireTrackEvidence:• Includestiretrackwidth,wheelbasedimensions,andturningdiameter• Tiretrackwidth=measurementmadefromcenterofonewheelorimpressiontocenteroftheopposite(NOTE:manyvehiclescansharethesame)
Images:http://www.centralia.edu/academics/forensicscience/FORS%20101/PowerPointPres/LTire.ppt
• Wheelbasedimensions=themeasurementbetweenthecentersofthehubsofthefrontwheelstothecenterofthehubsoftherearwheels(NOTE:rarelyisenoughinfodetailretainedatscenetodeterminethismeasurement)
Images:http://www.centralia.edu/academics/forensicscience/FORS%20101/PowerPointPres/LTire.ppt
• Turningdiameter=diameterofthecircleavehiclemakeswhensteeringwheelisfullyturned.(NOTE:canonlybeusedtoeliminatevehiclesthatcannotturnatleastthatsharply)
Images:http://www.centralia.edu/academics/forensicscience/FORS%20101/PowerPointPres/LTire.ppt
Turningdiameter=diameterofthecircleavehiclemakeswhensteeringwheelisfullyturned.(NOTE:canonlybeusedtoeliminatevehiclesthatcannotturnatleastthatsharply)
VII.RecoveryofTireEvidence:• First=generalcrimescenephotographs(lotsfrommanyangles),andnotes(numberoftracks,relationshiptooneanother,directionoftravel)
• Then=examinationqualityphotograph...thisisdoneinsamemannerasfootwearevidenceEXCEPTforlongertireimpressions...longerimpressionstakenassequentiallyoverlappingphotos.
(NOTE:allphotosshouldbetakenwithrulerorothersizereferencedeviceplacednextto,NEVERwithin,theimpression)
• Then=casting..anyimpression4ftorsmallershouldalwaysbecast...often,castoffersbestphysicalevidenceforlatercomparisonwithatire
Images:http://www.centralia.edu/academics/forensicscience/FORS%20101/PowerPointPres/LTire.ppt
VIII.TireEvidenceExamination:• Firstthetreadswillbecomparedwith...
• Knowntires
• Suspectvehicles...seizetiresfromvehicle,notingpositiononcar
• Eliminationvehicles(vehiclesknowntohavebeenatthescene,i.e.policecar)...apictureoftireisusuallyallthatisneeded
***tiredesignmostusefultoruleouttires• Thenifsimilardesign...thetiresmustbeanalyzedfurthertomakeamatch.• Todoso,willneedtomakeatestimpressionwithsuspecttire(s)...usuallydoneonclearmaterialsocanbesuperimposedonimpressionfromscene.
• Analysisincludes:• Closerlookattreaddesignelements,grooves,andsipes• Treaddimensionandtrackcharacteristics(NOTE:TreadDesignGuide andWhoMakesitandWhere listsissuedyearlyasreferencematerialaswellasadatabasetostorewheelbase,trackwidth,andturningradiuscanhelpcreatelistsofpossiblevehicles)
• Noisetreatmentandwearfeatures—usefultosignificantlynarrowdownthepossiblenumberoftires.Also,wearbarsandnoisetreatmentcanbeusedincombinationtolocateoreliminatetheareasofthetirethathavemadethesceneimpression.
• Randomindividualcharacteristicsordistinguishablemarks—includesstones,glass,nails,cutsandifpresentonbothimpressionandsuspecttire,thiscanallowforpositiveID
• Multipletiresofdifferentdesigns—whenfoundononevehicle,thelikelihoodoffindinganothervehiclewiththesamecombinationoftiredesignsissmallornonexistent.
SummaryandWrapUp
Givesomereasonswhytiretrackimpressionsareimportantatacrimescene.
GotoDiscoveryStreamingvideo:“ForensicDetectives:MysteriesandSolutions.”(2004)
Viewthefollowingtwoclipsonly:1-ExaminingTireTreadPrints[02:51]2-TireIdentification[02:07]