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Forensics

Forensics. Serology Day 8. This week in Forensics. Tuesday- Blood spatter Thursday- Test on Serology You should have back Blood packet #2. How do you calculate the angle of impact?. The shape of a blood stain: Round- if it falls straight down at a 90 o angle

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Forensics

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  1. Forensics Serology Day 8

  2. This week in Forensics • Tuesday- Blood spatter • Thursday- Test on Serology • You should have back Blood packet #2

  3. How do you calculate the angle of impact? • The shape of a blood stain: • Round- if it falls straight down at a 90o angle • The angle can be determined by: Width = sine of the impact Length

  4. What does the impact angle tell you? • The more acute the angle of impact, the more elongated the stain • 90o angles are perfectly round with 80o angels taking on a more elliptical shape • At about 30o the stain will begin to produce a tail • The more acute the angle, the easier it is to determine the direction of travel

  5. Today’s agenda • Make sure you turn in blood spatter labs 1 and 2 • Finish blood spatter lab 3 and the spatter practice worksheet- you’ll need to be able to calculate angles on your test Friday

  6. Forensic Files # 4 • What elements of a blood sample help identify a killer? • Which element has more probative value?

  7. Today’s agenda • Turn in the Sexual assault reading and Blood spatter technology assignment if you haven’t done so already • Blood spatter lab 1 • Blood spatter lab 2 • Papers are on table 1, supplies on table 4

  8. What is Blood Stain Spatter? • A field of forensic study which deals with the physical properties of blood and the patterns produced under different conditions as a result of various forces being applied to the blood • Blood, as a fluid, follows the laws of physics

  9. What are the characteristics of blood droplets? • Blood will remain spherical in space until it drops onto a surface • Once a blood droplet impacts a surface, a bloodstain is formed • A droplet falling from a height, hitting the same surface at the same angle, will produce a stain with the same basic shape

  10. What conditions effecting the shape of the bloodstain? • Size of the droplet • Angle of impact • Velocity at which blood droplet left the original surface • Texture of target surface

  11. What questions can be answered by blood spatter interpretation? • The distance between the target surface and the origin of blood at the time of blood shed • The point(s) of origin of the blood • Movement & direction of a person or an object • The number of blows, shots, etc. causing the bloodshed and/or the dispersal of blood

  12. What can the blood stains tell you? • The harder and less porous the surface, the less the blood drop falls apart • The softer and more porous the surface, the more a blood drop will break apart • The pointed end of the blood stain faces the direction the stain is traveling

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