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