 The use of physics and math to interpret bloodstain patterns within a forensic setting  May show: 1. Activity at scene 2. Number of blows 3. Position of victim and assailant 4. Whether death was immediate or delayed 5. Weapon characteristics

 Pitorowski wrote earliest reference to bloodstain pattern analysis  Balthazard was first to use physical interpretations of stains  Dr. Paul Kirkused bloodstain pattern interpretation as a defense witness in the Sam Shepherd case  Professor Herbert MacDonnell promoted bloodstain pattern interpretation as a tool for modern criminalistics  1983 – The International Association of Bloodstain Pattern Analysis was formed

 Package in NON-air tight container, such as a paper bag, so that no mold grows— dry blood can still be analyzed

 Circulates throughout body to transport oxygen, electrolytes, nourishment, hormones, vitamins, and antibodies to tissues an organs  Contains red blood cells (erythrocytes), white blood cells (leukocytes), plasma, and platelets  Held together by STRONG cohesive forces

 Does NOT fall in tear drop form (spherical)  Will not break apart as it falls through air  Is 6 times more viscous than water  Has average volume of 0.05 ml (diameter = 4.56 mm)  Blood hitting surface  --hard smooth surface = creates little spatter  --wood or concrete = create larger spatter (fig. 11.2, pg. 192)  Spattered blood = random distribution of bloodstains

 Allows for determination of area or location of origin of blood source (triangulation—see picture)  Place someone at a crime (on clothing)  ***May determine mechanism that created pattern (including speed of drop at impact, weapon used, direction of travel, angle of impact,)***

Notice the “top view”!

 LVIS—low impact velocity impact  Force = up to 5ft/sec  diameter= 4 mm+  Examples: blood drops into blood and footstep spatters

 MVIS—medium velocity impact  Force = 5-25 ft/sec  diameter = 1-3 mm  Examples: blood flicked off finger and blunt object used on victim

 HVIS—high velocity impact  Force = +100 ft  Diameter = < 1mm  Examples: gunshots and propellers

 Impact spatters: 1-Gunshot—mistlike pattern (<1mm blood spots) --Size range dependent on amount of blood, caliber of weapon, # of shots and location on body, hair/clothes --blowback or back spatter possible 2-Beating or stabbing—sizes 1-3 mm --depends on force and quantity of blood --only exposed blood makes spatter (not 1 st blow) --type of weapon influences pattern

 Direction of travel --Narrow end of elongated bloodstain points in direction of travel (impact angle < 90 degrees) --the tail will point in direction of travel --Circular bloodstain = no travel, 90 degree angle

 Impact Angle calculation (for elliptical bloodstains)  1 st find ratio of width to length (see picture)  Then take the arc sin of that ratio › Thus...  Angle of impact = sin -1 (width/length)

sin θ = W / L W L What does W = L mean? sin θ = 1 → θ = 90  Drop is a circle!

 90 degrees –  60 degrees –  30 degrees –  10 degrees –

 Closer for high velocity spatter or when stains originate closer to where the spatter occurred

 Rule of Thumb: As impact angle goes down, bloodstain shape becomes more elongated.

String Convergence in a 2 Dimensional Plane Convergence

 Transfer patterns (gun, knife, hand, foot…)  Void patterns (indicating some object was removed or a person was hit by spatter)  Flow patterns (may indicate movement with change in flow)

 Satellite or secondary spatter = single drops, circular or oval, 0.1=1 mm size  Drip pattern = multiple, free falling drops on horizontal surface  Castoff pattern = multiple blows to same area where wound has occurred and blood has accumulated

 Expirated patterns = blood that has pooled in lungs, sinuses, or airway passages is expelled from body  Arterial patterns = breaching of artery and result is gushing or spurts of blood  Blood transfer pattern = blood stained object contacts unstained object (can be a smear)  Dried blood = color changes... red –to— reddish brown —to— black

 Clotting time outside the body ranges from 3 – 15 minutes  Spattered clots indicate that time passed between the initial bleeding and later blows  Coughing of clotted blood may indicate post-injury survival of victim

 Drying begins at periphery and proceeds inward  Drying time is affected by › Surface type › Amount of blood › Climatic conditions  Skeletonization › Partially dry stains leave a ring that outlines original spatter › The drier the stain, the less skeletonization shown

 Document size, shape, and distribution of stains and patterns  Use photographs, video, diagrams, and notes  Collect articles of evidence with significant or questionable patterns (Remember Luminol can be used to detect or enhance bloodstain patterns)