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Bloodstain Pattern Analysis

Collection and Preservation of Evidence

Bloodstain Pattern Analysis 2

Goals

Students- will understand the importance of blood spatter evidence at a crime scene


ObjectivesStudents will:

Discuss what can be learned from bloodstain patterns

Explain the difference among low, medium, and high velocity spatters

Determine the direction of blood spatter and points of convergence



A field of forensic study that deals with the physical properties of blood and patterns produced under different conditions as a result of various forces being applied to the blood


Pop Quiz

Through Blood spatter analysis we can tell which of the following?A.B.C.D.



Enables reconstruction of events of the crime

A tool that can help prove who committed the crime



Can determine:Point(s) of originType of force usedNumber of blowsSequence of eventsPosition of victim and perpetratorMovement of people and objects



Determine direction blood was travelingConfirm/refute assumptions made by

investigators of events and their sequenceConfirm/refute statements made by witnesses

of events and their sequence



Factors that do not affect analysis:Age of bleeding personSex of bleeding personDisease present in bleeding personAlcohol level of bleeding personTemperature of scene Humidity of scene


Web Field TripDid you all remember to bring in your

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Click onto the ips address on the next slideMagically, you will be transported to our web

field trip siteWatch/listen to the video (it is 6 minutes long).Then COME BACK! – no skipping out, sneaking

off to the refrig, or checking out what is happening on TV!

When you return, we will resume class. :o)Bloodstain Pattern Analysis 13

Please click onto the ips address below:

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When attempting to reconstruct the events that led to bloodstain spatter, document:Size of the stainShape of the stainDistribution of stains in the pattern

Location of stains Direction of the stains Density of the stain



Diameter of a drop of blood depends on:Volume of the bloodDistance of the fallSurface texture


Surface Texture

18Bloodstain Pattern Analysis

Direction of Travel


Stain shape will indicate direction of travelRound – 90 degElongated - angleRound smooth end – toward the originTail end points in the direction of travel

Proper Documentation


Points of ConvergenceDrawing lines along long axis of several stains

will show a point of convergence at their origin


Area of Convergence


Impact Spatters

Impact Spatter: Bloodstain pattern normally consisting of small spots of blood, varying greatly in size and number, which results from a source of blood being subjected to an impact


Impact Spatters

Low Velocity Impact Spatter (LVIS)

Medium Velocity Impact Spatter (MVIS)

High Velocity Impact Spatter (HVIS)


Low Velocity Impact Spatter (LVIS)

Bloodstain pattern caused by a low velocity impact being applied to a source of blood

Sources:Open bleeding woundsObjects saturated with blood


Medium Velocity Impact Spatter (MVIS)

Bloodstain pattern caused by moderate amount of force applied to a source of blood

SourcesBeatingsFist, boot, baseball batKnifings

Drops may travel long distances


High Velocity Impact Spatter

Bloodstain pattern caused by high amount of force applied to source of blood

SourcesGunshotsExplosionMechanical accident (i.e. walking into airplane

propeller)Does not travel very far


Large Volume Bloodstain Patterns

Splashed PatternsRelatively large amounts of bloodReleased under influence of gravityTravels as a mass of blood until it hits a

surfaceAssociated with traumatic bleeding from

vessels under low pressure (veins)



Projected Pattern – Gush PatternRelatively large amount of bloodReleased under pressureAssociated with traumatic bleeding from

vessels under high pressure (artery)


Arterial Gush


Blood exiting the body due to traumatic bleeding (breached artery)



Projected Pattern


Blood into BloodCreated by drops of blood falling into pool of blood

or creating pool of blood as it fallsConsists of central pool of blood surrounded by

satellite stainsSatellite stains are usually circular and heavy in

appearanceCan easily be mistaken for impact splatter when

viewed only on a vertical surface (side of a tennis shoe)


Blood into Blood


Results from blood dripping into blood

Cast-Off Patterns

Created by blood thrown from a bloody object during “whip-like” termination of a back stroke

Characterized by linear (in-line) stain patternShape of drops change from round on the end

near origin to elongated at far endCan tell:

Minimum number of blowsWhere the killer was when the blows were

administered


Transfer/Contact Patterns

Transfer of blood from one object to another as result of contact

Recognizable imprint patterns can be created by contact with a bloody object


Transfer/Contact Pattern

Created when a wet bloody surface comes into contact with a second surface

39Bloodstain Pattern Analysis

Transfer/Contact PatternsSwipe - stain created when a bloody object contacts a non-bloody

surface in a swiping motion

Wipe - stain created when a non-bloody object wipes through a bloody surface


Swipe PatternTransfer of blood from a moving source onto

an unstained source (i.e. bloody hair)


Wipe PatternCreated when a non-bloody object wipes through a bloody surface


Trail Pattern

Results from drops of blood falling from a moving source of blood

Composed of drops of blood forming a trail of blood

Depending on speed of moving source of blood, the drops may show direction of travel


Trail Pattern


Voids and Limiting AnglesVoid – a pattern recognized by absence of

blood in an area where blood would be expected, denoted by a distinct border

Limiting Angle - can be used to limit location of the point of origin

Consider which surfaces have bloodstains Point of origin of a bloodstain is limited to the

area within range of that surface


Void Pattern


Recognized by the absence of blood in an area where blood would be expected, denoted by a distinct border


QUESTIONS????

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