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Blood Spatter Analysis and Glass

Science Olympiad 2013 Crime Busters

Jenna N

on 23 January 2013

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Transcript of Blood Spatter Analysis and Glass

What is Blood? Blood Spatter Analysis and Glass 2013 Science Olympiad Crime Busters Blood is the fluid that circulates in the heart,
arteries, capillaries, and veins of an organism, carrying nourishment and oxygen to, and bringing away waste products from all parts of the body. Blood Spatter Blood drops form various sizes and shapes
Blood spatter analysis uses the shapes and sizes to reconstruct the crime scene. Determining Distance Blood Falls Blood drops fall as small spheres
The size is dependent on the speed of the blood drop and the object used to cause the blood to drop.
Faster drop=larger size
Higher distance=larger size
The size also depends on the volume of the drop.
Volume depends on the object blood originated from (needle=small, bat=large) Effect Of The Surface Soft Surface=smooth sphere
Rough surfaces may cause some splatter Determining Direction Of Blood If more than one drop of splatter results, the point of origin can be determined. For each blood drop, a string can be guided back
to the point of origin. Splattered Blood Splattered Blood- random distribution of bloodstains that vary in size Amount of blood and amount of force can affect the size of blood spatter
Can help to determine of the origin of the blood source
Can result from gunshot, stabbing, beating, etc.
Can help determine the mechanism which created the pattern.
In general, for higher impacts, the pattern is more spread out and the individual stains are smaller.
Low Impact=beating High impact=gunshot Gunshot Spatter Gunshot spatter- can result in a mist like spatter that indicates a gunshot Not all gunshots will result in misting
If misting is present it is most likely a gunshot
Gunshots result in back spatter (where bullet enters) and forward spatter (where bullet exits) Beating and Stabbing Spatter Beating and Stabbing Spatter- larger individual stains First blow usually doesn't result in spatter since there is usually not any exposed blood.
Satellite Spatter Satellite Spatter- free falling drops of blood that fall onto a spatter pattern These drips are usually much larger than impact spatter.
However, blood dripping into blood can create a spatter. Castoff Pattern Castoff Pattern- Blood swung off a swinging object
Can reconstruct where assailant and victim were positioned Alteration Of Bloodstain Over Time Blood dries and clots over time
Difficult to estimate the time the blood exited the body
Clotted spears can indicate time of movement. Basic Classification Of Spatter Patterns This is based upon the velocity of the object causing the impact upon the blood source and the size of the resulting blood pattern or spatter evidence. Low Velocity- This type of spatter is usually caused by an impact to the blood source at a rate of 5 feet per second and is usually about 4 millimeters in diameter. Medium Velocity- Usually caused by an impact to the blood source at a rate of 5-25 feet per second: appears in a linear drop pattern High Velocity- Usually caused by an impact to the blood source over 100 feet per second: appear in random pattern NOW ONTO GLASS What Can Glass Do? Glass examiners could determine if a glass fragment is associated to another object in order to establish whether or not a particular person could be or could not be associated with: a.)a given place at a given moment
b.)a person
c.)an activity Glass Examinations Typical glass examinations involve the physical and optical measurements , such as thickness, density, dispersion, fluorescence, refractive index, etc.

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