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Blood Patterns

Blood Patterns. Forensic Science. A Brief Intro to Blood Spatter Analysis. Blood contains DNA, so it is possible to identify its exact source. The shape of the spatter indicates: the point of origin direction of travel, and angle of impact.

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Blood Patterns

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  1. Blood Patterns Forensic Science

  2. A Brief Intro to Blood Spatter Analysis • Blood contains DNA, so it is possible to identify its exact source. • The shape of the spatter indicates: • the point of origin • direction of travel, and • angle of impact. • Certain chemicals can detect the presence of blood even when it is not visible

  3. BLOOD TYPES • Four types of blood- A, B, AB, O Type A contains the A proteins Type B contains the B proteins Type AB contains both A & B proteins Type O contains neither A nor B proteins

  4. The Rh Factor • This is the + or – after the blood type A+, A-, O+, O-…and so on. + means the Rh protein is present, - means the Rh protein is absent

  5. BLOOD COMPATIBILITY • Type O- is the universal donor- all other blood types can accept type O blood • Type AB+ is the universal recipient- it can take all other types of blood

  6. MORE ON COMPATIBILITY Type O+: takes O- or O+ Type O-: takes O- Type A+: takes A+, A-, O+ or O- Type A-: takes A- or O- Type B+: takes B+, B-, O+ or O- Type B-: takes B- or O- Type AB+: takes A+, A-, B+, B-, AB+, AB-, O+, O- Type AB-: takes A-, B-, AB-, O-

  7. Basic Info on Shapes of Drops • The “tail” points in the direction of travel. • Drop at 90 degree angle will be circular. • Drop at less than 90 degree angle will be elliptical

  8. PRESERVING BLOOD EVIDENCE • Never place bloody evidence in plastic…it could promote mold growth and destroy the sample. • Blood soaked evidence should be placed in paper. NEXT: EXAMPLES OF BLOOD SPATTERS

  9. Arterial Blood

  10. Cast Off

  11. Drip

  12. Flow Pattern

  13. Hair Pattern

  14. Low Velocity

  15. Medium Velocity

  16. High Velocity

  17. Swipe Pattern

  18. Transfer from Hammer

  19. Transfer from Screwdriver

  20. Transfer from Fingers

  21. Transfer from Footwear

  22. Transfer from Knife Blade

  23. Wipe from Drying Blood Drop

  24. The EndReferences:Forensic Science: An Introduction to Scientific and Investigative Techniques by Stuart H. James & Jon J. NordbyImages from www.peelpolice.on.ca

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