Blood Spatter - Vegas Satisfies

Blood Spatterooooo11894 – Pitoroski wrote earliest reference toblood spatter analysis.1939—spatter patterns firstanalyzed by Balthazard (speed of bloodinfluences shape of the stain)Blood may spatter when a wound is inflictedBlood spatter pattern—a grouping of bloodstainsPatterns help to reconstruct the eventssurrounding a shooting, stabbing, or beatingForensic Science: Fundamentals & Investigations, Chapter 8

Blood Spatter AnalysisAnalysis of a spatter pattern can aid indetermining the:2 direction blood traveled angle of impact point of origin of the blood velocity of the blood manner of deathForensic Science: Fundamentals & Investigations, Chapter 8

Blood EvidenceooClass evidence for blood would include bloodtype. If you can determine the DNA youwould have individual evidence.Blood stain patterns are consideredcircumstantial evidence in a court room.Experts could argue many points includingdirection of stains, height of the perpetrator,position of the victim, left/right hand, whetherthe body was moved, etc.(usually only usedto enhance the argument)3

BLOOD DROPLETCharacteristicsoooA blood droplet will remain spherical in spaceuntil it drops onto a surfaceOnce a blood droplet impacts a surface, abloodstain is formed.A droplet falling from the same height, hittingthe same surface at the same angle, willproduce a stain with the same basic shape.4

BLOOD DROPLETVolumeooooIs approximately 0.05 ccIs not the same for all blood droplets--from0.03 cc to 0.15 ccIs directly dependent upon the surface ororifice from which it originatesThe impact area is called the target.5

CONDITIONS EFFECTINGBLOODSTAIN SHAPE1.2.3.4.Size of the dropletAngle of impactVelocity at which the blood droplet left theoriginal surfaceTexture of the target surface On clean glass or plastic--droplet will have smooth outsideedgesOn a rough surface--will produce scalloping on the edges6

Blood Splatter AnalysisNatural cohesiveness of blood – causes ablood droplet to fall in a spherical shape.Remember, over half of blood is waterCohesion: Water is attracted to waterAdhesion: Water is attracted to other substances7Forensic Science: Fundamentals & Investigations, Chapter 8

IMPACTooThe more acute theangle of impact, themore elongated thestain.90 degree anglesare perfectly roundwith 80 degreeangles taking on amore ellipticalshape.8

9Forensic Science: Fundamentals & Investigations, Chapter 8

Blood Splatter AnalysisoSatellite droplets— When blood falls from a height, or at a high velocity, It overcomes its natural cohesiveness, and Separates from the main dropletoSpiking patterns— Form around the dropletedges when blood fallsonto a less-than-smoothsurface10Forensic Science: Fundamentals & Investigations, Chapter 8

Bloodstain TerminologyoAngle of impact--angle at which blood strikes atarget surface.oBloodstain transfer--When a bloody object comesinto contact with a surface and leaves a patternedblood image on the surface.oBackspatter--blood that is directed back toward itssource of energy.oCast-off--blood that is thrown from an object inmotion11

Bloodstain TerminologyoContact stain--general term referring tobloodstains caused by contact between a wet, bloodbearing surface and a second surface which may ormay not have blood on it Transfer--image is recognizable and may beidentifiable with a particular object12

Bloodstain Terminology Swipe--wet blood is transferred to a surface whichdid not first have blood on it Wipe--a non-blood bearing object moves througha wet bloodstain, altering the appearance of theoriginal stain13

Bloodstain TerminologyoDirectionality--relates to the direction a drop ofblood traveled in space from its point of originoTerminal velocity--the greatest speed to which afree falling drop of blood can accelerate in air. It isdependent upon the acceleration of gravity and thefriction of the air against the blood--approximately25:1 feet/second.14

Bloodstain Terminology High velocity--greater than 100 feet per second;gives a fine mist appearanceLow velocity--5 feet per second or lessMedium velocity--5 to 25 feet per second.15

Bloodstain Patternooo16Terminal VelocityDirectionalityAngle of Impact

Blood Stain PatternsThe shape of a blood stain:llRound--if it falls straight down at a 90 degreeangle.Elliptical--Blood droplet elongates as the angledecreases from 90 to 0 degrees. The angle canbe determined by the following formula:width sine of the impact anglelength17

IMPACTooAt about 30 degreesthe stain will beginto produce a tail.The more acute theangle, the easier it isto determine thedirection of travel.18

Blood Splatter Analysis—DirectionalityThe shape of an individual drop of bloodprovides clues to the direction fromwhere the blood originated.How will the point of impact comparewith the rest of a blood pattern?19Forensic Science: Fundamentals & Investigations, Chapter 8

20Forensic Science: Fundamentals & Investigations, Chapter 8

Blood Splatter AnalysisLines of convergence—two or blood splatters canpinpoint the location of the blood source21Forensic Science: Fundamentals & Investigations, Chapter 8

22Forensic Science: Fundamentals & Investigations, Chapter 8

23Forensic Science: Fundamentals & Investigations, Chapter 8

Blood Splatter Analysis—Six PatternsDescribe each of these:a)b)c)d)e)f)24Passive drops (Drip Stain)Arterial gushesDirectional DropletTransferDrip TrailPoolsForensic Science: Fundamentals & Investigations, Chapter 8

Blood Splatter Analysis—Impactoo25Patterns can help investigators determinethe type of weapon usedWhat kind of a pattern is produced by a gunshot?What kind of a pattern is produced by ahammer blow?Forensic Science: Fundamentals & Investigations, Chapter 8

. . . . . . . . . . . . . . . . . Summaryoooo26Blood consists of cellular components and plasma.The various human blood types are caused by thepresence or absence of A and/or B proteins on thesurface of red blood cells.Blood splatter evidence can be used to recreate acrime scene.Investigators endeavor to (a) locate, (b) identify,and (c) interpret blood splatter patterns at crimescenes.Forensic Science: Fundamentals & Investigations, Chapter 8

1 Forensic Science: Fundamentals & Investigations, Chapter 8 Blood Spatter o 1894 – Pitoroski wrote earliest reference to blood spatter analysis. o 1939—spatter patterns first analyzed by Balthazard (speed of blood influences shape of the stain) o Blood may spatter when a wound is inflicted o Blood spatter pattern—a grouping of blood stains o Patterns help to reconstruct the events