Blood Found at Crime Scene Questions to ask: Is it really blood? Is the blood human? Who does the blood belong to? How did the blood get there? http://www.bloodsplatter.com/BPAtutorial.htm

Bloodstain Pattern Analysis What is the purpose? Reconstruct crime scene Position of victim Evidence of struggle Confirm (or refute) testimony Consistency with suspect statement How is BPA possible? Blood is a liquid subject to laws of physics! http://www.bloodsplatter.com/BPAtutorial.htm

Types of Blood Patterns Passive blood pattern created by gravity alone Transfer transfer blood from one surface to another by direct contact Projected blood subjected to source other than gravity http://www.bloodsplatter.com/BPAtutorial.htm

Passive Bloodstains Bloodstain is created with only the force of gravity drops drip patterns pools http://www.bloodsplatter.com/BPAtutorial.htm

Passive Bloodstains The appearance of a bloodstain may depend on the texture of the surface glass, linoleum, concrete absorbent materials: carpet, clothing, textiles

Transfer Bloodstains Bloodstain is the result of direct contact between a wet, bloody surface and another surface contact bleeding swipe or smear wipe smudge http://www.bloodsplatter.com/BPAtutorial.htm

Transfer Bloodstains May produce a recognizable image handprint, shoeprint http://www.bloodsplatter.com/BPAtutorial.htm

Projected Blood Blood subjected to action or force other than gravity Internally produced arterial spurt/gush Externally produced cast-off stain - thrown from a blood-covered object impact splatter - resulting from impact http://www.bloodsplatter.com/BPAtutorial.htm

Impact Splatter Size of blood stains depends on velocity Low Medium High

Directionality of Bloodstains When a spherical droplet of blood strikes a flat surface, the shape of the stain depends on the direction of travel and the impact angle. http://www.bloodsplatter.com/BPAtutorial.htm

Impact angle determination

Impact angle determination The shape of the stain can be used to calculate the impact angle: θ