Blood Spatter Analysis Bloodstains and Blood Spatter are used to reconstruct events that caused the bleeding.

Bloodstain Patterns can tell us…. Direction from which blood originated Angle at which a blood droplet struck a surface Location or position of a victim at the time a bloody wound was inflicted Movement of a bleeding individual at the crime scene Minimum number of blows that struck a bleeding victim Approximate location of an individual delivering blows that produced a bloodstain pattern

When determining the location the blood came from…. Surface texture Shape Size location

Surface Texture Harder and nonporous surfaces (glass, or smooth tile) -less spatter. Rough surfaces (wood, carpet) - irregularly shaped stains with serrated edges. Possibly with satellite spatter.

Satellite Spatter Small drops of blood around the perimeter of a drop or pool of blood. Produced as a result of blood impacting the target surface.

Direct and Angle of Impact

Direction of Impact The pointed end of a bloodstain always faces its direction of travel.

Blood Spatter A shooting may be characterized by both forward spatter from an exit wound and back spatter from an entrance wound.

Cast-off pattern A Cast-off pattern is created when a blood-covered object flings blood in an arc onto a nearby surface.

Types of Blood Spatter High velocity < 1mm Medium Velo medium velocity = 1-3 mm low velocity >3 mm Ex. Gun shot blunt trauma (knife, bat) blood dripping

Blood Spatter High Velocity < 1 mm Medium Velocity 1-3 mm Ex: Gun shot wound Medium Velocity 1-3 mm Ex: Blunt trauma (knife, bat) Low Velocity > 3mm. Ex: Dripping from wound

Void pattern Created when an object blocks the deposition of blood spatter onto a target surface or object. Examples: fingerprints, handprints, footprints, footwear prints, tool prints, and fabric prints in blood.

Transfer pattern Created when a surface that carries wet blood comes in contact with a second surface.

Cre-Creating a Spatter Guide We are going to be completing: Part I, II and VII

Conclusion Activity Example:

Determining Direction of Blood Blood Spatter > Direction Determining Direction of Blood The angle can be determined mathematically. Width/Length, then take the inverse sin (sin-1). This number is the impact angle (90 = perpendicular to surface; <10 at a sharp angle)

Determining Direction of Blood If more than one drop (from spatter) results, the point of convergence (2-D) can be determined

Blood Spatter > Direction For each blood drop, a string can be guided back to the point of origin (3-D).

11/19 Objective:  Review for Crime Scene Sketching and Blood Spatter Test DMA: Which blood drop would have the lowest angle of impact? A B C D