bloodstain pattern analysis
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Bloodstain Pattern Analysis. Collection and Preservation of Evidence. Goals. Students- will understand the importance of blood spatter evidence at a crime scene. Objectives. Students will: Discuss what can be learned from bloodstain patterns - PowerPoint PPT PresentationTRANSCRIPT
Bloodstain Pattern Analysis
Collection and Preservation of Evidence
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Goals
Students- will understand the importance of blood spatter evidence at a crime scene
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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
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Bloodstain Pattern Analysis
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
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Pop Quiz
Through Blood spatter analysis we can tell which of the following?A.B.C.D.
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Bloodstain Pattern Analysis
Enables reconstruction of events of the crime
A tool that can help prove who committed the crime
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Bloodstain Pattern Analysis
Can determine:Point(s) of originType of force usedNumber of blowsSequence of eventsPosition of victim and perpetratorMovement of people and objects
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Bloodstain Pattern Analysis
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
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Bloodstain Pattern Analysis
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
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Web Field TripDid you all remember to bring in your
permissions slips, signed by your mom?Here are the rules:
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:
http://www.youtube.com/watch?v=Od8YuwUT794
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Bloodstain Pattern Analysis
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
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Bloodstain Pattern Analysis
Diameter of a drop of blood depends on:Volume of the bloodDistance of the fallSurface texture
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Surface Texture
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Direction of Travel
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Stain shape will indicate direction of travelRound – 90 degElongated - angleRound smooth end – toward the originTail end points in the direction of travel
Proper Documentation
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Points of ConvergenceDrawing lines along long axis of several stains
will show a point of convergence at their origin
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Area of Convergence
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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
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Impact Spatters
Low Velocity Impact Spatter (LVIS)
Medium Velocity Impact Spatter (MVIS)
High Velocity Impact Spatter (HVIS)
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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
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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
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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
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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)
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Large Volume Bloodstain Patterns
Projected Pattern – Gush PatternRelatively large amount of bloodReleased under pressureAssociated with traumatic bleeding from
vessels under high pressure (artery)
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Arterial Gush
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Blood exiting the body due to traumatic bleeding (breached artery)
Large Volume Bloodstain Patterns
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Projected Pattern
Large Volume Bloodstain Patterns
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)
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Blood into Blood
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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
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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
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Transfer/Contact Pattern
Created when a wet bloody surface comes into contact with a second surface
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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
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Swipe PatternTransfer of blood from a moving source onto
an unstained source (i.e. bloody hair)
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Wipe PatternCreated when a non-bloody object wipes through a bloody surface
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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
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Trail Pattern
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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
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Void Pattern
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Recognized by the absence of blood in an area where blood would be expected, denoted by a distinct border
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QUESTIONS????