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Blood Stain Pattern Analysis
Transcript of Blood Stain Pattern Analysis
transport substances to and from cells
provide immunity and protection from viruses and bacteria, which are infectious
red blood cells determine our blood type
plateletes clump together to block openings in our vessels when injured
Introduction to BSPA
Blood Stain Pattern Analysis
Dexter doing what he does best
basics of blood: biological, chemical, physical
history of blood spatter
how blood spatter analysis works: determining angles of impact, point/area convergence, area origin
manner of death
bloodstain pattern analysis is basically using the law of physics, mathematics and biology to answer questions
how where what
Why have I chosen BSPA?
blood spatter can allow analyst to determine everything
all they need are blood droplets, their shape and angle of impact or amount
Dexter is an outstanding T.V show
Basics of Blood
Thicker than water
flows more slowly too
Temp of 100.4 degrees F
it's 8 % of your total body weight
5 to 6 liters in average male
4 to 5 liters in average female
consists of cellular material: 99% red blood cells with white blood cells
this includes: water, amino acids, proteins, carbohydrates, lipids, hormones, vitamins, electrolytes, dissolved gases, and cellular wastes
every red blood cell is hemoglobin
Just when did all this magic begin?
first known study of blood spatters: Dr. Eduard Piotrowski at the Institute for Forensic Medicine in Poland
cases including spatter interpretation began about 50 years later
State of Ohio v. Samuel Sheppard
now is standard practice of c.s.i
How Blood Spatter Analysis Works
all physical laws apply thanks to gravity
the resistance of a liquid to flow(viscosity)
surface tension is what creates the actual shape once it hits a surface
blood and air have molecules holding them all together
angles of impact, point of origin, and the point/area of convergence
spherical shape in flight helps with angle of impact
one blood drop will not determine the point of origin
when surface is struck and well shaped droplet formed analysist can study it
comes down to math.....
why does it come down to
" you may question...
alpha (α), the impact angle of the bloodstain path moving more outward like from the surface
beta (β), the angle of the bloodstain path pivoting around the vertical (z) axis
gamma (γ) is the angle of the bloodstain path measured from the plumb of the surface
displayed in a simple diagram.
what to look for
and even pools
Manner of Death
determining the difference between death by shotgun, bludgen, or blunt force trauma can be identified by the spatter evidence
when you put all the lines of blood together, wherever they converge, is the origin
"A void pattern is an absence of blood spatters in an area where you'd otherwise expect to see them. Often this void indicated where the attacker stood because his body prevented the blood from spattering on the surface behind him."
- The Forensic Science of CSI Katherine Ramsland