1. Blood Spatter Analysis Familiarization Training for the Scene Investigator Advanced Skills Investigative Branch 20 February 2008

2. What can blood stains tell us? Time of the crime Sequence of events Mechanism of injury Locations of persons and things Position of victims Corroborate testimony Advanced Skills Investigative Branch 20 February 2008

3. The Investigator’s Role Must have a basic understanding of the significance of bloodstain patterns – Initial evaluation – Proper documentation – Preservation of evidence Advanced Skills Investigative Branch 20 February 2008

4. Physical Considerations of Liquid Blood Advanced Skills Investigative Branch 20 February 2008

5. Stain Considerations Surface Tension Viscosity Gravity (or gravitational attraction) Velocity Surface on which it lands Advanced Skills Investigative Branch 20 February 2008

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11. Velocity Characteristics Low – Free-falling drops Medium – Blunt force ejection High – Firearm/Explosion Advanced Skills Investigative Branch 20 February 2008

12. Mechanisms of Deposition Passive – Clot, drip, flow, pool, saturation, serum separation Transfer – Swipes and wipes Projected – Arterial spurts, cast-off, expiratory, splashes Miscellaneous – Fly spots, voids, and skeletonized Advanced Skills Investigative Branch 20 February 2008

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15. Documentation Notes Sketches Measurements Photography – Photos used in interpretation Must be Normal to Surface – Include Scales in all shots Advanced Skills Investigative Branch 20 February 2008

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18. Interpretation Rules Impact vs Transfer on Textured Surfaces Age –Clotting –Drying –Color Advanced Skills Investigative Branch 20 February 2008

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23. Calculations and Interpretations Path of Blood Drop  L  = Impact Angle L = Length of Stain W = Width of Stain  = arc sin (W/L) Advanced Skills Investigative Branch 20 February 2008

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28. Summary What a stain can tell me? Investigator’s role Characteristics of liquid blood Mechanisms of deposition Documentation Calculation and Interpretation Advanced Skills Investigative Branch 20 February 2008