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]