Blood splatter Blood splatter analysis analysis the examination of the the examination of the shapes, locations, and shapes, locations, and distribution patterns of distribution patterns of bloodstains, in order to bloodstains, in order to provide an interpretation of provide an interpretation of the physical events which the physical events which gave rise to their origin gave rise to their origin
Blood splatter analysis. the examination of the shapes, locations, and distribution patterns of bloodstains, in order to provide an interpretation of the physical events which gave rise to their origin. History of Blood Spatter. 1894 – Pitoroski wrote the earliest reference to blood spatter - PowerPoint PPT Presentation
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Blood splatter analysisBlood splatter analysisthe examination of the shapes, the examination of the shapes,
locations, and distribution locations, and distribution patterns of bloodstains, in patterns of bloodstains, in
order to provide an order to provide an interpretation of the physical interpretation of the physical
events which gave rise to their events which gave rise to their originorigin
History of Blood SpatterHistory of Blood Spatter 1894 – Pitoroski wrote the earliest 1894 – Pitoroski wrote the earliest
reference to blood spatterreference to blood spatter 1939 – Balthazard first researcher to 1939 – Balthazard first researcher to
analyze the meaning of spatter patternanalyze the meaning of spatter pattern 1955 – blood spatter evidence used in 1955 – blood spatter evidence used in
the Sam Shepard case, helping to the Sam Shepard case, helping to exonerate himexonerate him
1971 – Dr. Herbert McDonnell used 1971 – Dr. Herbert McDonnell used blood-spatter analysis as tool in blood-spatter analysis as tool in forensic examinationforensic examination
How is it a source of forensic evidence?1. Origin(s) of bloodstain2. Distance of bloodstain from target3. Direction from which blood impacted4. Speed with which blood left its source5. Position of victim & assailant6. Movement of victim & assailant7. Number of blows/shots
Properties of Blood Volume On average, blood accounts for 8 % of total body
weight 5 to 6 liters of blood for males 4 to 5 liters of blood for
females A 40 percent blood volume loss, internally or/and
externally, is required to produce irreversible shock (death).
A blood loss of 1.5 liters, internally or externally, is required to cause incapacitation.
Properties of Blood
Why does a drop of blood have a curved surface when it lands on a flat surface instead of spreading out flat?
Why doesn’t it separate in the air before it hits the ground?
Gravity, cohesion, adhesion, surface tension
Properties of Blood Gravity: pulls it to ground
Droplet becomes longer than wide Cohesion: blood mixture is attracted to
similar blood mixtures and sticks together, not separates, as it falls Causes droplet to stay together
Adhesion: attractive forces of two different objects starts as teardrop because of adhesion
Surface Tension: the elastic like property of the surface of the liquid that makes it tend to contract, caused by the forces of attraction between the molecules of the liquid. Formation of a sphere
Porous surface – edge of drop of blood may form small spikes (extensions) or satellites Spikes – attached to make
droplet Satellites – not attached to main
droplet
Six Patterns Blood can be classified:
1. Passive Fall - Blood falling directly to floor at 90-degree angle will produce circular drops, with secondary satellites being more produced if surface hits is textured
Six Patterns Blood can be classified:
2. Arterial spurts or gushes – typically found on walls or ceilings caused by pumping action of the heart
3. Splashes – shaped like exclamation points. Shape and position of spatter pattern can
help locate the position of the victim at the time of the attack
Six Patterns Blood can be classified:
Six Patterns Blood can be classified:
4. Smears – left by bleeding victim depositing blood as he or she touches or brushes against a wall or furniture transfers
Six Patterns Blood can be classified:
5. Trails – can be left by bleeding victim depositing blood as he or she moves from one location to another. Can be round, smeared, appear as spurts
Six Patterns Blood can be classified:
6. Pools – form around victim who is bleeding heavily and remains in one place. If victim is moved to another location, there
may be droplets or smearing connecting the first location with a second
Spatter Patterns and Type of Wound High Velocity Impact (100 ft/sec) – fine-mist