L2.2 Bloodstain Patterns and Analysis

Vocabulary Term	Notes	Example
Bloodstain Pattern Analysis	The study and interpretation of bloodstains Analyzes patterns, shapes, sizes, and distribution of blood spatters Provides insight of 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 (often due to strong force)
Blood Splatter/Splash	Big volume of blood and concentrated (usually only gravity)
Drips	Bloodstains formed by the force of gravity acting on blood; creating droplets with well-defined shape (usually circular)
Flows	Bloodstains created by the movement of a volume of blood on a surface due to gravity
Swipe	Bloostains caused by object (rough/uneven) coming into contact with a surface and moving across it
Wipe	Resulting from object (smooth) moving through an existing wet bloodstain - appearance is wiping motion
Contact Patterns	Occur when a wet or bloody surface comes into contact with a second surface
Spatter	Resulting from forceful projection of blood and mst pattern 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. Pattern often shows series of arced or linear stains
Arterial Spurt	Bloodstains resulting from blood exiting an artery under pressure. Pattern is characterized by projecting, high-velocity streams of blood
Expirated Blood	Blodstains caused by blood forced by airflow out of the nose, mouth, or wound. Appear as fine mist-like droplets (sometimes bubbling)
Void	Absence of bloodstains in a specific area due to an object/person blocking bloods 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

Factors affecting bloodstains

Velocity	High velocity force → blood stains that are most-like/dispersed Low velocity force → bigger droplets and less dispersed
Surface	Nonporous and smooth surface →smooth edges and round circle Porous and rough surface → uneven edges and irregular shape
Angle of Impact	Angles in which blood droplets reached the surface can affect the shape of bloodstains; smaller the angle, more elongated shape is
Viscosity	Blood is thicker → allows it resist change in flow better
Temperature	High temp → blood less viscous coagulate faster, and evaporates faster Lower temp → blood more viscous, coagulate slower, and evaporates slower