Transcript Blood Spatter

Serology and BLOOD
Serology
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The study of body fluids
Examples…
Blood
Semen
Saliva
Sweat
Fecal matter
urine
Blood Trivia
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% of body weight
contributed to blood
 # of liters of blood in a
human body
 Amount of blood loss
that would cause
DEATH
 Amount of blood loss
would incapacitate a
human
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On average, 8 % of
total body
5-6 liters in men
4-5 liters in females
40 percent blood volume
loss, internally or/and
externally, is required to
produce irreversible
shock (death). That
would be 2000 ml
1.5 liters
Composition of blood
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White and red blood cells
Plasma (AKA serum
when re\moved from
body)
Antibodies (proteins
involved in an immune
response/attack)
Antigens (proteins on cell
membrane that cause an
immune response)
Proteins
Enzymes (peroxidase)
Platlets
3 questions to ask when a maroon/red liquid is
found at the scene
 Is
it Blood?
 Is it Human?
 Whose is it?
Is it Blood?
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Luminol Test
Reaction of peroxidase in
blood with luminol and a
base
forms a glowing
substance when test is
positive
Works to 3 x 10-9 dilution
Does not destroy blood
Is it Blood?
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Phenolphthalein/ Kastle Myer
Test
Reaction of Peroxidase (an
enzyme in blood to break
down H2O2) reacts with H2O2
Then solutionis reacted with
phenolphthalein, a positive test
shows up pink…just like CSI
However, it also turns pink in
the presence of potatoes or
horseradish, so care must be
taken at the scene.
Is it HUMAN???
 Immuno Assay
 Reaction
between antibodies and antigens
 Positive test when blood clots form
 Can be used to determine if blood is
another specific mammal
 Is also used for blood typing
Whose is it?
 DNA analysis
and use of
electrophoresis
must be done…..
 But that’s
another unit
Blood Spatter
What can blood spatter TELL US?
 ORIGIN
 Type
of weapon
 Direction blood was traveling
 Location & movement of victim and
assailant
 # of blows/gun shot wounds
Passive Vs. Active
Passive vs. Active Blood Loss
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Passive
Due to gravity
Dripping, oozing, pools
Low velocity
Usually large circular
drops
Passive terms:
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Drops
Drip patterns
Pools
Clots
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Projected
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An external or internal force
acting on blood
Spurting or gushing blood
Impact spatter
Can occur after death before
blood coagulates
Sources: stabbing,
beating,arterial spurt, cast off,
expirated blood ( FROM
LUNGS THROUGH
MOUTH/NOSE),
Med-high velocity
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Velocity of spatter
Relative
speed
Size of
spatter
(diameter)
Actual speed
Source
High velocity
< 1 mm
100 ft/sec
Gun shot
sneeze
Medium
velocity
1-4 mm
25 ft/sec
Beating
Stabbing
Cast off
Low velocity
4-6 mm
5 ft/sec
Passive loss
Passive vs. Active
Arterial Spurt
Spatter & Velocity
Transfer Blood Stains
TRANSFER BLOODSTAINS
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A transfer bloodstain is created when a wet, bloody
surface comes in contact with a secondary surface.
A recognizable image of all or a portion of the
original surface may be observed in the pattern,
as in the case of a bloody hand or footwear.
Transfer bloodstains can be further subdivided into;
• Contact bleeding
• Swipe or Smear
• Wipe
• Smudge
TARGET SURFACE TEXTURE
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type of surface the blood strikes
affects the amount of resulting
spatter,including the size and
appearance of the blood drops.
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Blood droplets that
strike a hard smooth
surface, like a piece
of glass, will have
little or no distortion
around the edge.
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Blood droplets that
strike a surface with
slight texture
( linoleum flooring) take
on a slightly different
appearance
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Scalloping will
occur around the
edge of the blood
droplets
Surfaces such as wood or concrete are
distorted to a larger extent. Notice the spikes
and secondary spatter present
Blood Spatter Vocab
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Splashes
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Smear
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Trails
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Pools
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Projected blood loss,
having a tail
 Left by bleeding
victim, touching
objects
 Passive, left by victim
when moving from
location to location
 Due to heavy passive
bleeding, in one place
More Vocab
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Spikes
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Poky, out juttings on a
blood drop
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Void pattern
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Absence of blood in an area of
spatter
Indicating that an object or a
person was in the path of the
blood
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Exsanguination
Cast Off
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Bleeding to death,
a.k.a. hypovolemic
shock
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Blood released or thrown from
a blood-bearing object in
motion
Cast Off
Which way did it go?
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You can determine the
direction that blood and other
liquids are traveling using tails
and satellites.
Tail: long projection on one
side of a drop
Satellite: small droplets
Tails and satellites will always
be on the front side of the
drop, or the side the blood
was moving toward
Directionality
Look for tails……….
Look for tails….
Point of Convergence
POINT OF CONVERGENCE
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The common point, on a 2 dimensional surface, over
which the directionality of several bloodstains can
be retraced.
Once the directionality of a group of stains has been
determined, it's possible to determine a two
dimensional point or area for the group of stains.
By drawing a line through the long axis of a group of
bloodstains the point of convergence
can be determined. Where the lines of the group of
stains intersect one another
the convergence point can be established.
Point OF ORIGIN
Analyze THIS ……….
With BLOOD Timing is
everything…
 Blood
begins to clot from 3 to 15 min.
outside of the body
 If blood is dark shiny and jelly-like it is less
than 60 minutes O.O.T.B.
 If the blood is clotted and contracts away
from plasma the blood is 2-5 hrs old
 This is just a rough guide