Blood Spatter Analysis Familiarization Training for the Scene

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

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 20 February 2008 Advanced Skills Investigative Branch

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

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

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

20 February 2008 Advanced Skills Investigative Branch

20 February 2008 Advanced Skills Investigative Branch

20 February 2008 Advanced Skills Investigative Branch

20 February 2008 Advanced Skills Investigative Branch

20 February 2008 Advanced Skills Investigative Branch

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

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 20 February 2008 Advanced Skills Investigative Branch

20 February 2008 Advanced Skills Investigative Branch

20 February 2008 Advanced Skills Investigative Branch

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

20 February 2008 Advanced Skills Investigative Branch

20 February 2008 Advanced Skills Investigative Branch

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

20 February 2008 Advanced Skills Investigative Branch

20 February 2008 Advanced Skills Investigative Branch

20 February 2008 Advanced Skills Investigative Branch

20 February 2008 Advanced Skills Investigative Branch

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

20 February 2008 Advanced Skills Investigative Branch

20 February 2008 Advanced Skills Investigative Branch

20 February 2008 Advanced Skills Investigative Branch

20 February 2008 Advanced Skills Investigative Branch

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