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Article Original Article

Using Multiple Void Patterns at Crime Scenes to Estimate Area of Origin in Bloodstain Cases

Article

Jeff Saviano, CFC, April Allgood, MS, and Zerah Malone, MS

Copyright: © 2010 Jeff Saviano, April Allgood, and Zerah Malone. Copyright for this article is retained by the authors with publication rights granted to the Association for Crime Scene Reconstruction. This is an Open Access article distributed under the terms of the Creative Commons Attribution-Noncommercial-No Derivatives License (http://creativecommons.org/licenses/by-nc-nd/3.0/) which permits unrestricted noncommercial use, distribution, and reproduction, provided the original work is properly cited and not changed in any way.

Introduction Void patterns, or the absence of

blood within an otherwise continuousbloodstainpattern,havebeentraditionallyusedby analysts for anumberofpurpos-es.Avoidiscausedwhenanintermediateobject intercepts the trajectory of blooddropletsinflight,whileontheirwaytoanotherwiseunobstructedfinaltargetsurface.A void can indicate, often by its distinctshape,theabsenceormovementofanob-jectthatwaspresentduringthebloodshed;andinmanycases,thephysicaldimensionsof that object.Void patternsmay also re-vealtheprecisepositionofclothingonanindividual at the time of the bloodlettingincident. (Wonder)The condition ofwin-dows and doors (open or closed and towhat degree) during bloodshed may alsobe determined.And, the locationof indi-vidualsatthetimebloodwasshedmaybe

concludedfromvoidsonsurfaceswithoth-erwise uninterrupted bloodstain patterns.Thisarticleexploresyetanotherreasonforexamining void patterns: to help estimatetheareaoforiginofaneventproducingaspatterpattern.

Void Pattern Shadow MatchingThe Void Pattern Shadow Matching

(VPSM) method involves the utilizationofacontrolledlightsourceinordertocastshadowswhichduplicatethevoidpatternsfoundatthecrimescene.Measurementsarethentakenofthepositionand locationofthelightsource,resultinginanestimateoftheareaoforigin(generallydefinedasthelocation in three-dimensional space fromwhichthespatteroriginated).Unlikeusingvoids todetermine the locationofobjectsafter they have been removed or reposi-tioned,VPSMrequiresthattheobjectscre-

Received: 03.22.2010Revised: 06.01.2010Accepted: 06.04.2010

Citation: Saviano, Jeff, April Allgood, and Zerah Malone. “Using Multiple Void Patterns at Crime Scenes to Estimate Area of Origin in Bloodstain Cases.” Journal of the Association for Crime Scene Reconstruction 16.3 (2010): 19-26.

Abstract:Voidpatternsinbloodstainpatternanalysisareoftenusedtodeterminetheabsenceormove-mentofanintermediateobjectfromitsoriginalpositionduringorafterabloodlettingevent.Thisar-ticleexaminestheuseofvoidpatternsasamethodofestimatingtheareaoforiginofeventsthatpro-ducebloodstains.Employmentofthismethod,whichtheauthorshavetermedtheVoidPatternShadowMatching (VPSM)method, canhelp the analyst or investigator at the scene to quickly determine anapproximateareaoforigin,whichcanlaterbeconfirmedbymathematicalanalysis.Keywords:bloodstainpatternanalysis,voidpatterns,voidpatternshadowmatching

Original Article

Original Articles

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atingthevoidsbepresentintheiroriginalpositions.

Theoretically,VPSMcouldbeusedwitha single void pattern at a scene; however,theprecision and accuracyof themethodis greatly increased when multiple voidpatterns, occurring on separate geometricplanes, are present. Due to this observa-tion,themorecomplexthephysicalaspectsof thesceneare, thebetter resultswillbeobtained usingVPSM. Figure 1 is an ex-ample of one type of complex scene inwhichVPSMcouldbeusedtobenefitthesceneinvestigatororanalyst.Notethatthescenecontainsnumerousobjectsofdiffer-entshapesanddimensions.Note,also,thattheobjectsarelocatedonseveraldifferentgeometricplanes in relation to theoverallscene.Assuch,spatterfromasinglebloodsource impacts only the exposed surfaceofeachoftheobjectsandcreatesmultiplevoidpatternsbehindthem.

Figures 2a and 2b are from the samecrimesceneasFigure1.Inthisexampletheelectricaloutlethasservedasanintermedi-atetargetproducingavoidpatternonthewallbehindit(illustratedbytherectangularoutline inFigure 2b).The locationof thevoid (aboveand to the rightof the recep-tacle)shouldsuggesttotheanalystthatthesourceofthebloodwas, ingeneralterms,belowand to the leftof theoutlet aspic-tured.TheuseofVPSMwouldprovidetheanalystatthescenewithamuchmorepre-ciseassessmentofthatareaoforigin.

Methods and MaterialsToexplore thepotential efficacyof the

Void Pattern Shadow Matching method,theauthorscreatedasimulatedcrimescenewith a target area consisting of a plasticshelving unit with three shelves, varioushouseholdobjectsplacedarbitrarilyontheshelves,andawallwhichwascoveredwithwhiteposterboardandlocatedbehindtheshelving unit. A sponge was affixed to astack of cinder blocks and positioned ap-proximately 28 inches (71 cm) from thebackwallandapproximately34inches(86cm)abovethefloor(seeFigure3).Mediumenergy impact spatter was then generatedbystrikingtheblood-soakedspongewitharubbermallet.Oncetheimpactspatterwascreated,thespongeandcinderblockswereremovedsothattheauthorscouldexaminethespatterandvoidpatterns.

Figure 1: This scene, in which objects and struc-tures of varying dimen-sions are found in different locations and on different geometric planes, lends itself to the use of the VPSM method for esti-mating area of origin.

Figure 2a (left): A void pat-tern is located above and to the right of the electri-cal receptacle.

Figure 2b (right): The void pattern from Figure 2a is outlined in red.

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Figure 3: Setup of simu-lated crime scene used for testing the VPSM method.

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Figure 4: One of the au-thors using a floodlight with reflector as a light source for creating shad-ows within the target area.

Figure 5: Multiple void patterns, which were caused by both the up-per shelf and the Triscuit® box, are shown to cor-respond with shadows created within the target area by use of the small LED flashlight.

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PursuanttotheVPSMmethod,variousportablelightsourceswereutilizedinorderto create shadows within the target area.Theauthorsemployedafloodlightwithre-flector(seeFigure4),ahandlanternwitha6Vblockbattery, anda smallLEDflash-light.Allthreemethodsproducedsatisfac-toryresults;however,itwasfoundthatthemorefocusedlightfromtheLEDflashlightproducedshadowsthatwerebetterdefinedand,therefore,easiertomatchtothevoidpatterns.

The light source wasmoved about thesceneuntilthelightcastshadowswhichdu-plicatedtheoutlineofthevoidpatternscre-atedbyboththehouseholdobjectsandtheshelving unit on which they were placed.

Inadjustingthepositionofthelight,effortwas made to duplicate multiple void pat-terns simultaneously. In order to achievethe greatest accuracy, one of the authorscontrolledthelightsource,whiletheothertwo(withfullviewofthetargetarea)pro-vided guidance regarding the positioningofthelight.Itshouldbenoted,also,thatallroom lightswere extinguished during theprocess in order to avoid any extraneousshadowscausedbylightingotherthantheintendedlightsources.

Figures 5a and 5b illustrate shadowsmatching void patterns in one portion ofthe target area.Note that the edgeof theupper shelf creates avoidon thewallbe-hindit;andatthesametime,theTriscuit®

Figure 5b: Red outlines il-lustrate the void patterns and corresponding shad-ows from Figure 5a.

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box creates a void on the shelf onwhichitsits,aswellasonthewall. Inmatchingthesemultiplevoidpatternsonmorethanonegeometricplane,VPSMallowedthefi-nalpositionofthe lightsourcewithinthescene to replicate the original position oftheblood-soakedsponge,whichwasaboveandtotherightoftheTriscuit®box.Oncetheprecisepositionofthelightsourcewasobtained, threemeasurements were takentodocumentthex,y,andzcoordinatesofthelightsourcewithinthescene,thusde-terminingtheareaoforiginforthespatter.In this experiment, these measurementsindicatedthatthexandy(horizontal)co-ordinates corresponded to those of theoriginal measured position of the blood-soaked sponge. The z coordinate of thelight sourcewas found tobe three inches(approximately 7.6 cm) above the originalposition of the sponge. This discrepancyintheverticalmeasurementwasnotfoundtobeproblematic,takingintoaccounttheparabolicarcoftheblooddropletsinflight.

Validation of ResultsOncetheareaoforiginwasdetermined

usingtheVPSMmethod,theauthorsrecal-culatedtheareaoforiginemployingmeth-odscurrently inusebybloodstainpatternanalysts: stringing; mathematical calcula-tions(tangentmethod);andcomputer-aidedanalysis (BackTrack™). In utilizing thesemethods,theauthorsdocumentedtheposi-tion and impact angles of 10well-formedstains, chosen from various locations onthe poster board. All three traditionalmethodsgaveresultsthatwerewithinfourinches(approximately10cm)oftheknownlocationofthebloodsource.Interestingly,thethreetraditionalmethodseachgavere-sultsthatdeviatedslightlyonthehorizontalplane,whiletheVPSMmethodshowednosuchdeviation.

Conclusions The Void Pattern Shadow Matching

(VPSM) method of determining area

of origin proved to be just as accurate (ifnotslightlymoreso)asthecurrentlyusedmethods of stringing, mathematical cal-culation, and computer-aided analysis. Itshouldbenotedhere,however,thatunlikethe traditional methods, VPSM requiresno mathematical calculations other thanmeasurements of thefinal positionof thelight source.Therefore, the additionalhu-manmeasurement and calculation factorsinvolved in the traditionalmethods (mea-suringtheshortandlongaxesofthestains,calculating angles of impact, determininggammaangles,andphysicallystringingtheblooddroplets’flightpaths), are likely thesources of the (perceived) increase in ac-curacyofVPSMover theothermethods.Furthermore,althoughtheprecisionofthemeasurementsinthisexperimentweredoc-umentedinsomecasestotwodecimalplac-es,theareaoforiginderivedbyanyofthefourmethodswouldhavebeenreportedasapproximationsor adimensional range inactual casework.As such, it couldbe saidthatallfourmethodsreturnedresultsthatwereanalogoustooneanother.

The advantages of using the VPSMmethodareseveral.First,VPSMprovidesaquickandaccuratealternativetotraditionalmethods,andcanbeusedtoeasilyestimatetheareaoforiginofimpactspatterwhilethecrimesceneisstillbeingprocessed.Inthiswayitcanbeaninvestigativetoolthatmaybehelpful infurtherevaluatingthescene,or in interviewingwitnessesandsuspects.Themethod requires no equipmentotherthanalightsource(e.g.anLEDflashlight)andatapemeasure;thus,itiseasilyacces-sibletoanycrimesceneinvestigatorwitharudimentaryknowledgeofbloodstainpat-ternanalysis.ThefinaltargetsurfaceislesscriticalwithVPSMthanitiswithtradition-almethods,since theanalyst isonly iden-tifyingvoidpatternsandnotlookingforasufficientnumberofwell-formedstainstouse for impact angle calculations. Finally,VPSM requires fewermeasurements than

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thetraditionalmethods;therefore,reducingthelikelihoodofhumanerror.Ithasbeenshown,forexample,thatmeasurementer-ror,particularlyregardingstains thathaveimpactedthetargetsurfaceatanglesgreaterthan50degrees,canresultinafairlylargediscrepancy in calculated impact angles.(Pace)

DiscussionTheauthorsseetheVoidPatternShadow

Matchingmethodasan investigative tool,which can provide the analyst or investi-gatorwith immediate results at the crimescene. It’s important to note, however,that a competent and experienced blood-stainpatternanalyst,usingoneormoreofthe traditionalmethods, shouldverify theVPSMresultsbeforetestimonyisgiveninacourtproceeding,particularlyiftheVPSMmethodwas used by someone other thanacourt-qualifiedexpert inbloodstainpat-tern analysis. To that end, the scene andthebloodstainpatternsshouldstillbethor-oughlydocumentedtosuchadegreethatatraditional bloodstain pattern analysis canbeperformed.

The authors feel that additional experi-mentation with VPSM is warranted andshould be carried out by independent re-searchers. Included among the goals offurther researchwouldbe the explorationoftheeffectsoftwodifferentvariables:thedistance between the object creating thevoidpatternandthesurfaceonwhichthevoidpatternisfound;andthedistancebe-tweenthebloodsourceandthevoid-creat-inginterveningtarget(s).Itishypothesizedbytheauthorsthatthecloserthevoid-cre-atingobjectistothetargetsurfacecontain-ingthevoidpattern,thesharperwillbethedelineationof thevoid itself.Therefore, itshouldbeeasiertovisualizethecorrespon-dencebetweenthevoidandtheshadowincaseswheretheintermediatetargetisclos-esttothetargetsurfacecontainingthevoid.

Itisfurtherhypothesizedthatthefartherthebloodsourceisfromthetargetarea,thelessaccuratetheareaoforiginwillbe.Thisisbasedonconsiderationof theparabolicarcdescribedbyeachoftheblooddroplets.Blooddropletsofsimilarvolumeandmass,whichtravelafartherdistancewithoutbe-ing intercepted by an intermediate target(thus,spendingmoretimeintheair)areex-pectedtobemoresusceptibletoredirectionby the forces of gravity and air resistancethanthosetravelingashorterdistanceforashorterperiodoftime.( James)Depend-ingonthelengthoftheflightpath,thefi-nal segmentof theblooddroplet’s coursemaybe sharplydownward,which is likelyto affect the position and dimensions ofthevoidpattern.Therefore,incaseswherethebloodsourceisaconsiderabledistancefromthetargetarea,twophenomenawouldbe expected to occur. First, the void pat-terns themselveswould be less delineatedandmorediffuse—aphenomenoncausedbythearcofsomeoftheblooddropletsal-lowingthemtocleartheintermediatetargetandstrikethefinaltargetsurfaceatpointsthatwouldotherwise be devoidof blood.Second, the area of origin determined byVPSM would be expected to be higher(have an increased z coordinate) than theoriginalpositionoftheactualbloodsource.Inthemethodologyusedforthisarticle,

allthreeauthorswereawareofthelocationofthebloodsourcepriortotheutilizationoftheVPSMmethodforfindingtheareaoforigin.Futureexperimentationandvali-dationstudiesshouldincludeablindproce-dureinwhichoneormoreanalystswouldnotbepresentduringthedepositionofthebloodandcreationofthevoidpatterns.Insuchascenariothebloodsourcewouldberemoved prior to the VPSM analysis andsubsequentverificationbytraditionalmeth-ods,andtheresultsof theanalyseswouldbecheckedagainst theknown locationofthebloodsource.

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Finally, although the blood source asfoundbytheVPSMmethodcanbedocu-mentedsimplybytheuseofatapemeasureandthoroughnote taking, futureresearchmightincludeamethodforphotographical-lydocumentingtheVPSManalysis.Ambi-entlightphotographsmightbeconsideredinwhichthecamerawouldbeplacedonatripodandpositioned,forexample,behindthe lightsource (perpendicular to the tar-getarea),aswellastothesideofthelightsource (parallel to the target area) in or-dertodocumentthelocationofthebloodsource as determined by VPSM. This re-searchcouldalsoincluderecommendationsforcameraandlenstypes,aswellasforex-posuresettings.

Certainly,notallcrimesceneswill lendthemselvestotheVPSMmethod.Theana-lyst or investigator will have to evaluateeachscenetodetermineifVPSMwillbeofbenefit to the investigation. In the future,with adequate validation, VPSM may, insomecircumstances,beabletoreplaceoneormoreof the traditionalmethodsofde-terminingareaoforigin.Fornow,howev-er,incaseswherethephysicalaspectsandconfigurationofthescenesuggestthatthistypeofanalysiswouldbebeneficial,VPSMcanserveasausefuladditiontothecrimesceneinvestigator’sanalytictoolbox.

ReferencesJames, Stuart H., Paul E. Kish, and T.Paulette Sutton. Principles of Bloodstain Pat-tern Analysis Theory and Practice.BocaRaton:CRCPress,2005.

Pace, Alexi. “The Relationship BetweenErrorsinEllipseFittingandtheIncreasingDegree ofError inAngle of ImpactCal-culations.”IABPA News,September2005:pages12–14.

Wonder,Anita.Blood Dynamics.SanDiego:AcademicPress,2001.