Blood Spatter Mrs. L. Fox

Bloodstain Formation Examining the pattern of the bloodstain can reveal The direction from which blood originated The angle at which a blood droplet struck a surface The location or position of a victim at the time a bloody wound was inflicted The movement of a bleeding individual at the crime scene The minimum # of blows that were struck The approximate location of an individual delivering the blows

Surface Texture Harder & nonporous surfaces result in less spatter Glass & smooth tile Rough surfaces usually result in irregularly shaped stains with serrated edges Possibly with satellite spatter

Tests for the Presence of Blood Police want to answer three questions: Is this blood? Is it from a human? How closely does it match the blood of the victim or the suspect?

Tests for the Presence of Blood Presumptive tests for blood Lumino l: sprayed directly on bloodstained object; produces a glow when it contacts blood

Direction & Angle of Impact As stain becomes more elliptical, its direction become more discernable. Pointed end of stain faces direction of travel The smaller the angle (compared to the surface), the more elongated the stain.

Impact Spatter When an object impacts a source of blood That spatter projected outward and away (exit wounds, for example) is called Forward Spatter Blood coming back toward the source of the impact is Back Spatter Velocity of Spatter Low velocity – bigger drops Medium velocity – smaller drops High-velocity – very fine drops, like a spray Typically produced by gunshot or explosions

Other Spatter Cast-off – created when a perpetrator raises an object to take another swing, and some of the blood is flung off the weapon Arterial spray – created when an artery is nicked or torn, and the heart pumps it out fast