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Bloodstain Pattern Analysis

Bloodstain Pattern Analysis. Blood Spatter > Direction. Determining Direction of Blood. Narrow end of a blood drop will point in the direction of travel. Blood Spatter > Direction. Determining Direction of Blood. This is a 2-dimensional point of origin.

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Bloodstain Pattern Analysis

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  1. Bloodstain Pattern Analysis

  2. Blood Spatter > Direction Determining Direction of Blood Narrow end of a blood drop will point in the direction of travel.

  3. Blood Spatter > Direction Determining Direction of Blood This is a 2-dimensional point of origin. It is possible to determine the 3-D point of origin

  4. Blood Spatter > Direction • For each blood drop, a string can be guided back to the point of origin.

  5. Blood Spatter > Direction Determining Angle of Impact • The angle can be determined mathematically. • Width/Length, then take the inverse sin (sin-1). • This number is the impact angle (90 = perpendicular to surface; <10 at a sharp angle)

  6. Blood Spatter Types of Spatter • Spattered Blood = random distribution of bloodstains that vary in size • Amount of blood and amount of force affect the size of blood spatter. • Can result from gunshot, stabbing, beating

  7. Blood Spatter Spattered Blood can: • Help determine the location of the victim, asailant, and origin of blood. • Help determine the mechanism which created the pattern.

  8. Blood Splatter Analysis—Six Patterns Describe each of these based on the images above: a. passive drops b. arterial gushes c. splashes d. smears e. trails f. pools

  9. Blood Spatter Spattered Blood In general, for higher impacts, the pattern is more spread out and the individual stains are smaller. Low impact = beating High impact = gunshot

  10. Blood Spatter Types of 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.

  11. Blood Spatter Gunshot Spatter Gunshots result in back spatter (where bullet enters) and forward spatter (where bullet exits).

  12. Blood Spatter Types of Spatter Beating and Stabbing Spatter = larger individual stains First blow usually doesn’t result in spatter since there is not yet any exposed blood.

  13. Blood Spatter Types of Spatter Castoff Pattern = Blood flung off of swinging object. Can reconstruct where assailant and victim were positioned.

  14. Blood Spatter Types of Spatter Expirated Bloodstain Pattern = Blood can accumulate in lungs, sinuses, and airway. Forcibly exhaled. • Can appear like beating or gunshot pattern. • May be mixed with saliva or nasal secretions.

  15. Blood Spatter Alteration of bloodstain over time • Blood dries and clots over time. • Difficult to estimate the time the blood exited the body. • Clotted smears can indicate time of movement.

  16. Blood Splatter Analysis—Impact Patterns can help investigators determine the type of weapon used. • What kind of a pattern is produced by a gun shot? • What kind of a pattern is produced by a hammer blow?

  17. Low Velocity Impact Spatter (LVIS) A bloodstain pattern that is caused by a low velocity impact/force to a blood source. Description This pattern was generated by stepping onto a small pool pattern on the target. Low velocity impact spatter (LVIS) is generally produced by objects travelling less than 1.5 m/s. The majority of stains in this pattern are larger than 3 mm in diameter. There may also be spines radiating from the parent stain. In this example, the shoe came in contact with the bottom portion of the pool first.

  18. Medium Velocity Impact Spatter (MVIS) A bloodstain pattern caused by a medium velocity impact/force to a blood source. A beating typically causes this type of spatter. Description This pattern was generated by placing a small volume of blood on a hard surface and striking it with a rubber mallet. Medium velocity impact spatter (MVIS) is generally produced by objects travelling between 1.5 m/s and 7.5 m/s. The majority of stains in this pattern are between 1 mm and 3 mm in diameter. This type of pattern is most often associated with blunt force trauma or cutting/stabbing actions.

  19. High Velocity Impact Spatter (HVIS) A bloodstain pattern caused by a high velocity impact/force to a blood source such as that produced by gunshot or high speed machinery. Description This pattern was generated using a fan on high speed and dropping blood into the mechanism at an angle that allowed the blood to strike the target. High velocity impact spatter (HVIS) is generally produced by objects travelling greater than 30 m/s. The majority of the resulting bloodstains are smaller than 1 mm in diameter. This type of pattern is most often associated with gun shot wounds and industrial machinery.

  20. Void An absence of stains in an otherwise continuous bloodstain pattern. Description This pattern was generated by placing a small funnel on top of the target. A fan was then set on medium speed and blood was dropped into the mechanism at an angle that allowed it to strike the target. The funnel was then removed. It may be possible to determine what object was present during the bloodshed by looking at the void it created after it was removed. It may also be possible to determine the sequence of events by looking at void patterns.

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