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EVIDENCE Basics of Blood Spatters

EVIDENCE Basics of Blood Spatters. Blood left at a crime scene functions as evidence. Blood spatter analysis takes time and is just one piece of the crime scene puzzle. Bloodstain pattern analysis often corroborates other evidence and gives investigators critical evidence.

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EVIDENCE Basics of Blood Spatters

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  1. EVIDENCEBasics of Blood Spatters mwaldrop@2012

  2. Blood left at a crime scene functions as evidence. Blood spatter analysis takes time and is just one piece of the crime scene puzzle. mwaldrop@2012

  3. Bloodstain pattern analysis often corroborates other evidence and gives investigators critical evidence. mwaldrop@2012

  4. Bloodstain Analysis can indicate: Type and velocity of weapon Number of blows Handedness of suspect Position and movements of suspect and victim Which wounds were inflicted first Type of injuries How long ago the crime was committed Whether death was immediate or delayed mwaldrop@2012

  5. Blood spatters can assist us with recreating the crime. Blood leaves the body as a liquid that follows the laws of motion and gravity. mwaldrop@2012

  6. Blood molecules are very cohesive (attracted to each other), so they squeeze against each other until they form the smallest shape possible. They travel in spherical drops because of this attraction mwaldrop@2012

  7. Blood drops behave in PREDICTABLE ways when they strike a surface or force acts upon them. mwaldrop@2012

  8. Why is it important that the blood acts in predictable ways to be used as evidence? mwaldrop@2012

  9. Over time, blood spatters dry. How quickly this happens, depends upon what surface it lands on, how much blood is contained in the splatter, and the heat and humidity of the crime scene. mwaldrop@2012

  10. A very dry blood spatter can SKELETONIZE. Skeletonize means to flake off and leave a ring around the original diameter of the spatter. mwaldrop@2012

  11. A blood spatter analyst can help determine the time of the crime based on the dryness of the blood. mwaldrop@2012

  12. Although initially blood behaves as a liquid, it begins to clot soon after it leaves the body.As soon as 15 minutes! mwaldrop@2012

  13. If blood spatters are more clotted than others, it can indicate that multiple blows or gunshots occurred over a period of time. mwaldrop@2012

  14. Blood spatters can also contain pieces of bone and tissue. This is usually prevalent in high impact spatters. mwaldrop@2012

  15. Low Velocity Spatter Low Velocity: Results in dripping blood Force of impact is 5 feet per second or less Size of droplets are between 4 and 8 millimeters mwaldrop@2012

  16. Low Velocity Spatters Often occur after the victim has sustained the injury – not during the infliction. mwaldrop@2012

  17. Low Velocity Spatter Example Victim is stabbed and then walks around bleeding. The resulting spatters are called PASSIVE SPATTERS mwaldrop@2012

  18. Low velocity spatters can also result in pools of blood left around the victim, and TRANSFERS. Transfers are impressions left by weapons, or smears and trails left by movement. mwaldrop@2012

  19. Medium Velocity SpatterForce is from 5 – 100 feet per secondDiameter of drop is between 1 – 4 millimeters. mwaldrop@2012

  20. Medium Velocity Spatter Caused by blunt objects such as a bat or an intense beating with a fist. mwaldrop@2012

  21. Medium Velocity Spatter In a stabbing, arteries are often nicked and the victim bleeds faster. Blood spurts from wounds as the victims heart continues to beat. This is called PROJECTED BLOOD. mwaldrop@2012

  22. High Velocity Spatters usually come from a gunshot wound.Velocity: More than 100 feet per secondDroplets are less than 1 millimeter in diameter. mwaldrop@2012

  23. Bullet wounds are unique because they can have both back and front spatters or just back spatters.This depends on whether the bullet exits the body. mwaldrop@2012

  24. High velocity spatter can be caused by any instrument of high velocity. mwaldrop@2012

  25. VOIDS: Empty space not covered in blood This indicates that something or someone caught the blood spatter. mwaldrop@2012

  26. In addition to size and force of impact, the SHAPE of the spatter is important as well. mwaldrop@2012

  27. Stippling: burns on skin from gunpowder. Shots fired from close range can also cause INTERNAL MUZZLE STAINING. Internal Muzzle Staining is when a victim’s blood is sucked back into the gun’s muzzle. mwaldrop@2012

  28. Stringing: Attaching strings to each spatter to see where they converge (or come together). mwaldrop@2012

  29. Using an elastic string, the analyst draws lines from each spatter through a level line. mwaldrop@2012

  30. Then, he or she uses a protractor on the level line in the area where the strings converge to determine the angle of flight. mwaldrop@2012

  31. Analysts use trigonometric functions to find the area of convergence. mwaldrop@2012

  32. History of Blood Spatter Analysis Dr. Eduard Piotrowski did the first known study at the Institute for Forensic Medicine in Poland in late 1890’s. mwaldrop@2012

  33. It wasn’t until State of Ohio v. Samuel Sheppard (1955), that blood spatter analysis was used as evidence in court by Dr. Paul Kirk. mwaldrop@2012

  34. Dr. Herbert MacDonellpublished “Flight Characteristics of Human Blood and Stain Patterns” in 1971. mwaldrop@2012

  35. It has now become standard practice for law enforcement officials to include blood spatter analysis in a crime scene investigation. mwaldrop@2012

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