Download Blood Stain Analysis

Blood stain pattern analysis
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Blood spatter analysis is performed by forensics experts at crime scenes where
impact on a body has caused blood land on surrounding surfaces: this evidence
can be used to reconstruct the crime scene.
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When blood is not immediately obvious at a crime scene (i.e. attempts have
been made to wash it away), a chemical called luminol can be sprayed over
the area. Luminol reacts with the iron in haemoglobin in a chemiluminescent
reaction to emit blue light.
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The use of physics to interpret bloodstain patterns within a forensic setting
may show:
1. Activity at scene
2. Number of blows struck
3. Position of victim and assailant
4. If death was immediate or delayed
5. Weapon characteristics
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Experiments have shown that blood tends to form into a sphere rather than a
teardrop shape when free falling or projected in drop size volume.
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Types of bloodstains:
o Passive bloodstains
 Drips, pools
o Projected bloodstains
 Arterial spurting
 Expiratory blood (coughing)
o Transfer bloodstains
 Wipe marks
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Blood clots within 3-15 minutes of being outside the body.
o Spattered clotted blood indicates time between blows
o Coughed clotted blood indicates post injury survival of victim
o Wet blood is more useful than dried blood as can test drug and alcohol
content.
Blood facts:
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Functions of blood:
o nourishment
o hormones
o antibodies
o heat
o supplies o_______ to the body
o carries away waste matter
o carries away c_______ d_______
Blood is made up of the following cell types:
____________________________________
Red blood cells contain h_____________ which carries o___________ around
the body.
The average blood volume of an adult is ______ litres and makes up about
____% of your body weight.
There are ____ main blood types: ________________________________
Experiment:
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Demonstrate low, medium and high velocity blood spatter