http://soinc.org/forensics_noteshttp://soinc.org/sites/default/files/uploaded_files/forensics/For_Forensics_Web_Sites.pdf

RulesInRound

SolidsFlowchartTableofPropertiesPicturesApplications

PolymersTableofPropertiesHair

Chromatography/SpectroscopyPhysicalEvidence

FingerprintAnalysisDNAGlassAnalysisEntomologySpattersSeeds,tracks,andsoilBloodBulletstriations

Analysis

SolidsFlowchart

TableofProperties

Pictures

SodiumBicarbonate

SodiumChloride

SodiumCarbonate:

LithiumChloride:

PotassiumChloride:

CalciumSulfate:

CalciumNitrate:

CalciumCarbonate:

Cornstarch: Glucose: Sucrose

MagnesiumSulfate:

BoricAcid:

AmmoniumChloride:

Applications:

Polymers TableofProperties

Plastic Abbr. Density OtherKeyFeatures CommonlyUsedtoMake

Polystyrene PS ~1.05g/cm^3

Polymerizesbyaddition,reactswithacetone

styrofoam,tableware,coffeecups,toys,lighting,signs,

insulation

Polypropylene PP ~0.90g/cm^3

Polymerizesbyaddition foodcontainers,medicinecontainers,automobilebatteries,carpet,rope,

plasticwrap,labequipment

PolyvinylChloride PVC ~1.38g/cm^3

Burnsgreen,polymerizesbyaddition

foodpackaging,shampoocontainers,construction

(ahemPVCpipes...youseethemoften),tiles,credit

cards

LowDensityPolyethylene

LDPE ~0.92g/cm^3

Polymerizesbyaddition,ethylenemonomerunits

branchoutmorethanHDPE

foodcontainers(specificallybags),grocerybags,plastic

wrap,etc.

HighDensityPolyethylene

HDPE ~0.95g/cm^3

Polymerizesbyaddition,monomerunitsmorelinear

foodcontainers,bags,lumber,furniture,flower

pots,signs,trashcans,toys

Polycarbonate PC ~1.20g/cm^3

Polymerizesbycondensation,clear

shatterproofglass,eyeglasslenses

PolyethyleneTerephthalate

PETE ~1.37g/cm^3

Polymerizesbycondensation,shrivelswithheat

softdrinkbottles,carpet,fiberfill,rope,scouringpads,fabric,Mylar

PolymethylMethacrylate

PMMA ~1.16g/cm^3

Polymerizesbyaddition,reactswithacetone

Plexiglas,glasssubstitute

Fibers

Fiber Type Fact BurnTestResults MicroscopicView

Wool Animal Mostcommonlyusedanimal

shrivels,leavesbrownblackresidue,smellslikeburninghair/grass

cylinderwithscales

fiber,dissolvesinbleach

Silk Animal Smootherthanwool,dissolves

inbleach

shrivels,leavesblackresidue,smellslikeburningmeat,leavesblackbead>black

powder(likewool)

thin,longandsmoothcylinder

Cotton Vegetable

Mostwidelyusedplantfiber,fairlyshortfibers

burnswithasteadyflame,smellslikeburningpaper,abletoblowflamefromthreadlikeamatch,leavesacharred

whitishash

irregulartwistedribbon

Linen Vegetable

fibersgenerallylongerand

smootherthancotton

burnsataconstantrate,doesnotproducesmoke,smellslikeburninggrass,

producessparks

smooth,bamboolikestructure

Polyester Synthetic fiberscanbeanylength

melts,onlyigniteswhenintheflame,dripswhenitburnsandbondsquicklytoanysurfaceitdripson,producessweet

odorandhard,colored(sameasfiber)ash

completelysmoothcylinder

Nylon Synthetic longfibers curls,melts,producesblackresidue,smellslikeburningplastic(somesourcessayitsmellslikecelery?),ignitesonly

whenbroughtintoflame

fine,round,smooth,

translucent

Spandex Synthetic canstretchtoeighttimesitsoriginallength

meltsquickly,softblackash,chemicalodor

Flattened,ridgedfibers,

clustered

Hair:

Cathairisusuallyfinerthanhumanhairordoghair.Doghaircanbeoftwodifferentkinds.Theoutercoatisgenerallyverycoarseandoftenstraight.Theundercoatisoftenfineandcanbeverycurly.Inhumanhair,thecolorofthehaircanmakeadifferencetoo.Generallyspeaking,darkhairisthickerthanblondhairandredhairisthefinest.

Hairfolliclesgrowinrepeatedcycles.Onecyclecanbebrokendownintothreephases.1)AnagenGrowthPhase2)CatagenTransitionalphase3)TelogenRestingPhase

Eachhairpassesthroughthephasesindependentoftheneighboringhairs.AnagenPhaseGrowthPhaseApproximately85%ofallhairsareinthegrowingphaseatanyonetime.TheAnagenphaseorgrowthphasecanvaryfromtwotosixyears.Hairgrowsapproximately10cmperyearandanyindividualhairisunlikelytogrowmorethanonemeterlong.CatagenPhasetransitionalphaseAttheendoftheAnagenphasethehairsentersintoaCatagenphasewhichlastsaboutoneortwoweeks,duringtheCatagenphasethehairfollicleshrinkstoabout1/6ofthenormallength.Thelowerpartisdestroyedandthedermalpapillabreaksawaytorestbelow.TelogenPhaserestingphaseTherestingphasefollowsthecatagenphaseandnormallylastsabout56weeks.Duringthistimethehairdoesnotgrowbutstaysattachedtothefolliclewhilethedermalpapillastaysinarestingphasebelowhttp://soinc.org/sites/default/files/uploaded_files/forensics/For_Hair&Fiber.pdfhttp://soinc.org/sites/default/files/uploaded_files/forensics/For_Hair_Analysis2.pdf

Chromatography:ChromatographyFormula:Rf=p/swherethevariable"p"isthedistancethepigment(theinkorjuice)travels(measuredfromthecenterofthecolorband)andthevariable"s"isthedistancethesolvent(usuallywateroracetone)travels.

MassSpectrometryTheyaxisisameasureofthepercentabundanceThexaxisisthem/zratio(molarmass)Thelinesareknownaspeaks.Readinggraphsofmassspec::1)Searchforamolecularionpeakfirst.Itmaynotalwaysbepresent,butcommonlyisthelargestpeak,exceptforisotopicpeaks.TheNominalMolecularWeight(MW)isaroundedvalueassignedtothemoleculerepresentingtheclosestwholenumbertothemolecularweight.ThisvalueisevenifthecompoundbeinganalyzedcontainssimplyCarbon,Hydrogen,Oxygen,Sulfur,orSilicon.ThevaluewillbeoddifanyoftheseelementsarecombinedwithanoddnumberofNitrogen.2)Attempttocalculatethechemicalformula,usingisotopicpeaksandusingthisorder:LookforA+2elements:O,Si,S,Cl,BrLookforA+1elements:C,NAndthen:"A"elements:H,F,P,I.Fromlookingattheisotopicpeaks,itispossibletodeterminerelativeabundanceofspecificelements.3)Calculatethetotalnumberofringsplusdoublebonds:Forthemolecularformula:CxHyNzOnrings+doublebonds=x(1/2)y+(1/2)z+14)Trytodeterminethemolecularstructurebaseduponabundanceofisotopesandm/zof

fragments.http://www.chemguide.co.uk/analysis/masspec/howitworks.html

PhysicalEvidenceFingerprints:

Thereareeightfingerprintpatternstoknow.Theyare:PlainWhorl,UlnarLoop,RadialLoop,PlainArch,TentedArch,CentralPocketLoop,DoubleLoop,AccidentalWhorl

Whorlshavetwoormoredeltas.Thepresenceofmorethantwodeltasindicatesanaccidentalwhorl.

Loopshaveonlyonedelta.Thedifferencebetweenanulnarloopandaradialloopisthatulnarloops"enterandexit"onthesidefacingthepinky(thesideofthewristcontainingtheulna)whileradialloopsdosoonthesidefacingthethumb(thesideofthewristcontainingtheradius).

Archeshavenodeltas.Tentedarchesareeasilydistinguishablebythetriangularcore.

MethodsofDevelopment

Latentprintsmustbedevelopedinordertobeseen.Therearefourcommonmethodsandonelesscommonmethod:

Dusting:Powderappliedtoprintsstickstofattyacidsandlipids.

IodineFuming:Selfexplanatorybyitsname.Itwasoneoftheearliestmethodsoffingerprintdevelopment.Theiodinereactswithbodyfatsandoilsinprints.

Ninhydrin:achemicalmethodusefulforliftinglatentprintsonpaper.Itreactswithaminoacidsinprints.

Cyanoacrylate(Superglue)Fuming:Alsoselfexplanatorybyitsname.Italsoreactswithmoistureintheairaswellasreactingwithsubstancesintheprints,formingstickywhitematerial

alongridges.Goodfornonporoussurfaces.

SmallParticleReagent(SPR):Notascommonastheothermethodsused,butstillimportant.SPRisusedforwetsurfacesandreactswiththelipidspresentinfingerprints.

Features

DNAAlthoughmanycompetitionsthathaveincludeDNAasevidencerequirematchingofDNAfingerprints,questionsaboutbasicDNAphysiologyandprinciplescomeupalongwiththem.PCR(PolymeraseChainReaction),amethodofsyntheticDNAreplication,alsocomesupsometimes.

ThefournucleotidesthatcomposeDNAareadenine,cytosine,thymine,andguanine.

WithaDNAfingerprint,largerfragmentsofDNAarelocatedontherightsidewhilesmalleronesarelocatedontheleft.Thisisbecauseofgelelectrophoresis,whichmakethefingerprints.Whenthecurrentrunsthroughthegelduringthisprocess,becauseDNAisnegativelycharged,itwillmovetowardsthepositiveendofthebox.SmallerfragmentsofDNAwillobviouslymovefartherthroughthegelfilterthanlargerones.

PCR,asalreadystated,standsforPolymeraseChain

ReactionitisamethodofsyntheticDNAreplicationdevelopedinthelate20thcentury.PCRhasbeenverycrucialtomolecularbiologyandforensics,thenandnow,soitsdevelopmentearnedaNobelPrize.

Glass:

Iftheglass'srefractiveindexisthesameorclosetothatofaliquid,thenthepieceofglasswillnot

bevisibleinthatliquid(useexactsameliquidsthatareusedforplastics)

Fractures:Cracksendatexistingcracks,Asmallforceformscircularcracks,Radialcracksandchonchoidalcracksmakerightangles,butfacedifferentways.Whendealingwithfractures,rememberthe3Rsofglassfracture:RadialcracksatRightanglesontheReversesideofimpact,Aforceveryclosetotheglassbeforeimpact,suchasagunshotorarock,willcompletelyshattertheglass

Entomology:FreshStage:Stagesofinsectsfoundonadeadbodycantellhowlongthevictimhasbeendead.Themostcommonaretheblowflyandthebeetle.Blowfliesappearfirst,withinminutesorhoursofthedeath.Fleshfliescanarriveatthesametimeasblowflies,butgenerallyarriveslightlylater.Certainamountsoftimelapsebetweeneachlifestage,whichcantellthistime.Forexample,ifonlymaggotswerefoundonthedeadbody,thatmeansthevictimprobablydiedlessthantwentyfourhoursago.Beetlesusuallyarrivewellaftertheblowandfleshflies,andaregenerallythelastinsectleftonthebodyaftermonthsofdecomposition.Mitesarealsogenerallypresentwiththesebeetlesinitiallybecausetheyhelpsuppressmaggots,andassuchallowcertaintypesofbeetles.

Spatters

LowVelocityFormation.

Appearstobedroplikeandformsatspeedslessthen5f/s

MediumVelocityFormation

Appearsinalineartypeofdroppattern525f/s

HighVelocityFormation

Appearsinessentiallyarandompatternaround100f/s

AngleofImpact:Theangleatwhichaspatterhitsasurface.Theformulaforitis:=arcsin(W/L),Wheretheta()istheangle,Wisthewidthofthespatter,andListhelengthAreaofOrigin:The3dareawherethebloodcamefrom,HAoO=dtan(AoI),HisheightaboveAreaofConvergence(wherethelongaxesofthespattersmeet)

http://www.crimesceneinvestigator.net/SimplifiedGuideBloodstainPatterns.pdf

Seeds,Soil,Tracks,Pollen

SeedsandPollen:Inthissectionofthecompetition,almostnopracticeisneeded.Theparticipantsmustbeabletocomparetheevidencefromthecrimescenetothatwhichisfoundonthesuspects.Theymayalsoberequiredtomatchcertaintypesofseedsorpollenstoaregionofthenationorworld,whichisgenerallycommonsense.Itis,however,helpfultohaveageneralknowledgeaboutvariouskindsofpollenandcommonregionallyidentifiableplants.Thismayincludeplantssuchascottonorrice,whichcanonlygrowinspecificclimates.

Tracks:Inthissection,mostobservationswillbequalitative.Often,theonlynecessaryactionistocomparethegivenphotographstothetrackprovidedatthe"scene."Thesetrackscanbefootprintsortiretracks,bothofwhichcanbeidentifiedbythetreadthatisleftontheground.Checkingthepattern,shape,andsizeofeachdistinctpartofthesoleonashoeisgenerallynecessarytomakea100%accuratematch.

Soil:Soilcanbeusedasawaytopossiblyconnectasuspecttothegeneralareaofthecrime.Forexample,ifthecrimewascommittedatthebeach(howeverunlikelyitis),andonesuspecthadsandonhim,thenyoucouldpossiblyinferthatthesuspectwasnearthesceneofthecrime.

BloodUsingAntigenAandAntigenBserums,itispossibletofindanybloodtype.IfthebloodreactswiththeAantigenonly,thenitistypeA.IfitreactsonlywithBantigen,itistype.Ifitreactswithboth,thenthebloodtypeisAB,andifitreactswithnoneofthetestingliquids,thenitisO.ABistheleastcommonbloodtype,O+themostLuminol(C8H7N3O2)isusedtopickuptracesofbloodatacrimesceneit+anoxidantwillfluoresceinthepresenceofacatalystsuchashemoglobin

BulletStriations

Bulletstriationsareprettymuchjustliketracks.Prettymuchtheonlythingyouhavetodoistrytomatchtheoneofthesuspects'bulletstriationtothatoftheonefoundatthescene.

Analysis

Rules

InRound

010 1020 2030 3040 4050

Liam SolidID SolidID Chromatography

misc Looseends

Saba PhysicalEvidence

PhysicalEvidence

Polymers writtenanalysis Finishanalysis