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Bloodstain Pattern Analysis

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

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Bloodstain Pattern Analysis

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  1. 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 Bloodstain Pattern Analysis

  3. Objectives • Students 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 Bloodstain Pattern Analysis

  4. Bloodstain Pattern Analysis

  5. Bloodstain Pattern Analysis

  6. 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 Bloodstain Pattern Analysis

  7. Pop Quiz • Through Blood spatter analysis we can tell which of the following? • A. • B. • C. • D. Bloodstain Pattern Analysis

  8. Bloodstain Pattern Analysis • Enables reconstruction of events of the crime • A tool that can help prove who committed the crime Bloodstain Pattern Analysis

  9. Bloodstain Pattern Analysis • Can determine: • Point(s) of origin • Type of force used • Number of blows • Sequence of events • Position of victim and perpetrator • Movement of people and objects Bloodstain Pattern Analysis

  10. Bloodstain Pattern Analysis • Determine direction blood was traveling • Confirm/refute assumptions made by investigators of events and their sequence • Confirm/refute statements made by witnesses of events and their sequence Bloodstain Pattern Analysis

  11. Bloodstain Pattern Analysis • Factors that do not affect analysis: • Age of bleeding person • Sex of bleeding person • Disease present in bleeding person • Alcohol level of bleeding person • Temperature of scene • Humidity of scene Bloodstain Pattern Analysis

  12. Web Field Trip • Did 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 slide • Magically, you will be transported to our web field trip site • Watch/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 Bloodstain Pattern Analysis

  14. Bloodstain Pattern Analysis • When attempting to reconstruct the events that led to bloodstain spatter, document: • Size of the stain • Shape of the stain • Distribution of stains in the pattern • Location of stains • Direction of the stains • Density of the stain Bloodstain Pattern Analysis

  15. Bloodstain Pattern Analysis • Diameter of a drop of blood depends on: • Volume of the blood • Distance of the fall • Surface texture Bloodstain Pattern Analysis

  16. Bloodstain Pattern Analysis

  17. Surface Texture Bloodstain Pattern Analysis

  18. Stain shape will indicate direction of travel Round – 90 deg Elongated - angle Round smooth end – toward the origin Tail end points in the direction of travel Direction of Travel Bloodstain Pattern Analysis

  19. Proper Documentation Bloodstain Pattern Analysis

  20. Points of Convergence • Drawing lines along long axis of several stains will show a point of convergence at their origin Bloodstain Pattern Analysis

  21. Area of Convergence Bloodstain Pattern Analysis

  22. 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 Bloodstain Pattern Analysis

  23. Impact Spatters • Low Velocity Impact Spatter (LVIS) • Medium Velocity Impact Spatter (MVIS) • High Velocity Impact Spatter (HVIS) Bloodstain Pattern Analysis

  24. Low Velocity Impact Spatter (LVIS) • Bloodstain pattern caused by a low velocity impact being applied to a source of blood • Sources: • Open bleeding wounds • Objects saturated with blood Bloodstain Pattern Analysis

  25. Low Velocity Impact Spatter Bloodstain Pattern Analysis

  26. Medium Velocity Impact Spatter (MVIS) • Bloodstain pattern caused by moderate amount of force applied to a source of blood • Sources • Beatings • Fist, boot, baseball bat • Knifings • Drops may travel long distances Bloodstain Pattern Analysis

  27. Medium Velocity Impact Spatter Bloodstain Pattern Analysis

  28. High Velocity Impact Spatter • Bloodstain pattern caused by high amount of force applied to source of blood • Sources • Gunshots • Explosion • Mechanical accident (i.e. walking into airplane propeller) • Does not travel very far Bloodstain Pattern Analysis

  29. High Velocity Impact Spatter Bloodstain Pattern Analysis

  30. Large Volume Bloodstain Patterns • Splashed Patterns • Relatively large amounts of blood • Released under influence of gravity • Travels as a mass of blood until it hits a surface • Associated with traumatic bleeding from vessels under low pressure (veins) Bloodstain Pattern Analysis

  31. Large Volume Bloodstain Patterns • Projected Pattern – Gush Pattern • Relatively large amount of blood • Released under pressure • Associated with traumatic bleeding from vessels under high pressure (artery) Bloodstain Pattern Analysis

  32. Blood exiting the body due to traumatic bleeding (breached artery) Arterial Gush Bloodstain Pattern Analysis

  33. Projected Pattern Large Volume Bloodstain Patterns Bloodstain Pattern Analysis

  34. Large Volume Bloodstain Patterns • Blood into Blood • Created by drops of blood falling into pool of blood or creating pool of blood as it falls • Consists of central pool of blood surrounded by satellite stains • Satellite stains are usually circular and heavy in appearance • Can easily be mistaken for impact splatter when viewed only on a vertical surface (side of a tennis shoe) Bloodstain Pattern Analysis

  35. Results from blood dripping into blood Blood into Blood Bloodstain Pattern Analysis

  36. 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 pattern • Shape of drops change from round on the end near origin to elongated at far end • Can tell: • Minimum number of blows • Where the killer was when the blows were administered Bloodstain Pattern Analysis

  37. 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 Bloodstain Pattern Analysis

  38. Transfer/Contact Pattern • Created when a wet bloody surface comes into contact with a second surface Bloodstain Pattern Analysis

  39. Transfer/Contact Patterns • Swipe - 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 Bloodstain Pattern Analysis

  40. Swipe Pattern • Transfer of blood from a moving source onto an unstained source (i.e. bloody hair) Bloodstain Pattern Analysis

  41. Wipe Pattern • Created when a non-bloody object wipes through a bloody surface Bloodstain Pattern Analysis

  42. 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 Bloodstain Pattern Analysis

  43. Trail Pattern Bloodstain Pattern Analysis

  44. Voids and Limiting Angles • Void – 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 Bloodstain Pattern Analysis

  45. Recognized by the absence of blood in an area where blood would be expected, denoted by a distinct border Void Pattern Bloodstain Pattern Analysis

  46. QUESTIONS???? Bloodstain Pattern Analysis

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