L2.2 Bloodstain Patterns and Analysis

Bloodstain Pattern Analysis

The study and interpretation of bloodstains, analyzing patterns, shapes, sizes, and distribution to provide insight into how and where bloodshed occurred.

Antigens

Outside substances that can be recognized by antibodies.

Antibodies

Triggers an immune response from leukocytes.

Blood Spatter

Small droplets and dispersed blood, often due to strong force.

Blood Splatter/Splash

Big volume of blood that is concentrated, usually only affected by gravity.

Drips

Bloodstains formed by the force of gravity acting on blood, creating well-defined circular droplets.

Flows

Bloodstains created by the movement of a volume of blood on a surface due to gravity.

Swipe

Bloodstains caused by a rough/uneven object coming into contact with a surface and moving across it.

Wipe

Resulting from a smooth object moving through an existing wet bloodstain, creating a wiping motion appearance.

Contact Patterns

Occur when a wet or bloody surface comes into contact with a second surface.

Spatter

Resulting from the forceful projection of blood, often due to a high velocity impact or force.

Cast-off

Bloodstains created when a blood-covered object flings blood onto surfaces while in motion; often shows series of arced or linear stains.

Arterial Spurt

Bloodstains resulting from blood exiting an artery under pressure, characterized by projecting, high-velocity streams of blood.

Expirated Blood

Bloodstains caused by blood forced by airflow out of the nose, mouth, or wound; appear as fine mist-like droplets.

Void

Absence of bloodstains in a specific area due to an object or person blocking blood's trajectory.

Satellites

Small blood stains surrounding a central bloodstain due to the ejection of blood droplets upon impact.

Spines

Elongated patterns from a central bloodstain; resulting from blood droplets contacting a non-smooth surface.

Velocity

High velocity force leads to blood stains that are small and dispersed; low velocity results in bigger droplets that are less dispersed.

Surface

Nonporous and smooth surfaces create smooth edges and round circles, while porous and rough surfaces produce uneven edges and irregular shapes.

Angle of Impact

The angle at which blood droplets reach the surface can affect their shape; smaller angles result in more elongated shapes.

Viscosity

Thicker blood allows it to resist changes in flow better.

Temperature

High temperature makes blood less viscous, coagulate faster, and evaporate quicker; low temperature makes blood more viscous, coagulate slower, and evaporate slower.