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Blood Spatter Blood Spatter AnalysisAnalysis
General RulesGeneral Rules
Directionality of a blood drop while in Directionality of a blood drop while in flight is usually obvious from the flight is usually obvious from the geometry of its resulting bloodstain. The geometry of its resulting bloodstain. The pointed end indicates the direction pointed end indicates the direction of of travel prior to impact on a surface. travel prior to impact on a surface.
General RulesGeneral Rules
The shape of a bloodstain is a function of The shape of a bloodstain is a function of the angle at which it impacts a surface. the angle at which it impacts a surface. Perfectly round Perfectly round bloodstains result from bloodstains result from a a ninety degree ninety degree impact. The angle of impact. The angle of impact of an impact of an ellipticalelliptical bloodstain may bloodstain may calculated from its calculated from its length to width length to width ratio. ratio.
Impact spatterImpact spatter:: High velocityHigh velocity Medium velocityMedium velocity Low velocityLow velocity
Cast off PatternCast off Pattern From bloody objectFrom bloody object
Arterial SpurtingArterial Spurting From arteryFrom artery
Transfer PatternTransfer Pattern SwipeSwipe Wipe Wipe
Passive PatternPassive Pattern Gravity aloneGravity alone
TARGET SURFACE TARGET SURFACE TEXTURE TEXTURE
Bloodstains can occur on a variety of Bloodstains can occur on a variety of surfaces, such as carpet, wood, tile, surfaces, such as carpet, wood, tile, wallpaper,wallpaper,clothing,clothing, etc… etc…
The type of surface the blood strikes The type of surface the blood strikes affects the amount of resulting affects the amount of resulting spatter,spatter,including the size and appearance of including the size and appearance of the blood drops.the blood drops.
TARGET SURFACE TARGET SURFACE TEXTURETEXTURE
Blood droplets that Blood droplets that strike a hard strike a hard smooth surface, smooth surface, like a piece of like a piece of glass, will have glass, will have little or no little or no distortion around distortion around the edge.the edge.
General RulesGeneral Rules
Surface tension Surface tension prevents spattering prevents spattering regardless of the distance a drop of blood regardless of the distance a drop of blood has fallen before impacting a smooth, has fallen before impacting a smooth, hard surface such as glass. hard surface such as glass.
TARGET SURFACE TARGET SURFACE TEXTURETEXTURE
Blood droplets that Blood droplets that strike a fairly hard strike a fairly hard surface.. From a surface.. From a distance. Will show distance. Will show a distinct a distinct appearance. appearance. ((scallopingscalloping) around ) around the edge of the the edge of the blood droplets.blood droplets.
And And raysrays And satelite dropsAnd satelite drops
TARGET SURFACE TARGET SURFACE TEXTURETEXTURE
Surfaces such as Surfaces such as wood or concrete wood or concrete are distorted to a are distorted to a larger extent.larger extent. Notice the spinesNotice the spinesand secondary and secondary spatter present.spatter present.
Non spatter:Non spatter:
Transfer patternsTransfer patterns SwipeSwipe wipewipe
PassivePassive Gravity onlyGravity only
Changes with timeChanges with time SettleSettle ClotClot Dry Dry
Dried bloodDried blood
Clotted BloodClotted Blood
Blood DripBlood Drip
TRANSFER BLOODSTAINSTRANSFER BLOODSTAINS
Swipe: A transfer bloodstain is Swipe: A transfer bloodstain is created when a wet, bloody object created when a wet, bloody object comes in contact with a secondary comes in contact with a secondary surface.surface.
Wipe: An object moves through an Wipe: An object moves through an existing stain.existing stain.
TRANSFER TRANSFER BLOODSTAINS: SwipeBLOODSTAINS: Swipe
Transfer pattern: wipeTransfer pattern: wipe
PASSIVE BLOODSTAINSPASSIVE BLOODSTAINS
Passive Passive Bloodstains are Bloodstains are drops created or drops created or formed by the force formed by the force of gravity acting of gravity acting alone.alone.
Spatter: PROJECTED Spatter: PROJECTED BLOODSTAINSBLOODSTAINS
Projected bloodstains are created Projected bloodstains are created when a blood source (victim) is when a blood source (victim) is subjected to a forcesubjected to a force
The size, shape, and number of The size, shape, and number of resulting stains will depend, primarily, resulting stains will depend, primarily, on the amount of force utilized to on the amount of force utilized to strike the blood source.strike the blood source.
SPATTER PatternsSPATTER Patterns
Spatter patternsSpatter patterns High velocityHigh velocity Medium velocityMedium velocity Low velocityLow velocity
Arterial SpurtingArterial Spurting Cast offCast off
Arterial SpatterArterial Spatter
Arterial Spurt / Arterial Spurt / GushGush
Bloodstain Bloodstain pattern(s) resulting pattern(s) resulting from blood exiting from blood exiting the body under the body under pressure from an pressure from an artery (heart)artery (heart)
Cast Off PatternCast Off Pattern
Cast-off StainsCast-off Stains Blood released or thrown from a blood-Blood released or thrown from a blood-
bearing object in motionbearing object in motion
General RulesGeneral Rules
The The smaller the size smaller the size of bloodspatters, of bloodspatters, the the greater the energy greater the energy required to required to produce them. Low, medium, and high produce them. Low, medium, and high velocity impact spatter may be identified velocity impact spatter may be identified by their respective sizes. by their respective sizes.
PROJECTED PROJECTED BLOODSTAINS - ImpactBLOODSTAINS - Impact
Low VelocityLow Velocity Gravitational pull Gravitational pull
up toup to 5 feet/sec.5 feet/sec. Relatively large Relatively large
stainsstains 4mm in size 4mm in size and greaterand greater
General RulesGeneral Rules
When the preponderance of individual When the preponderance of individual bloodstains are approximately bloodstains are approximately 1mm or 1mm or more in diamerer,more in diamerer, they have been they have been produced by a produced by a medium velocity medium velocity impactimpact. Most often they would result . Most often they would result from a beating or stabbing. from a beating or stabbing.
PROJECTED PROJECTED BLOODSTAINS - ImpactBLOODSTAINS - Impact
Medium VelocityMedium Velocity Force of 5 to 25 Force of 5 to 25
feet/sec.feet/sec. Preponderant stain Preponderant stain
sizesize 1 to 4mm in 1 to 4mm in sizesize
General RulesGeneral Rules
When the preponderance of individual When the preponderance of individual bloodstain diameters are bloodstain diameters are less than 1mmless than 1mm, they , they have been produced as a result of a have been produced as a result of a high high velocity impactvelocity impact. Most often they would result . Most often they would result from a shooting. from a shooting.
PROJECTED PROJECTED BLOODSTAINS - ImpactBLOODSTAINS - Impact
High VelocityHigh Velocity Force of 100 Force of 100
feet/sec. andfeet/sec. and greatergreater
Preponderant stain Preponderant stain sizesize 1mm in size 1mm in size and smallerand smaller
Mist-like Mist-like appearanceappearance