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Trace Evidence Project

Published on Nov 21, 2015

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PRESENTATION OUTLINE

Trace Evidence Project

by: Collin Mcaden and Nate Nyakundi
Photo by Inventorchris

BLOOD: CHEMICAL AND PHYSICAL PROPERTIES

  • High oxygen content: bright red; Low oxygen content: dark red .
  • Glows in visible CLU light, feels sticky
  • Blood is made up of plasma, white blood cells, and red blood cells.
Photo by ˙Cаvin 〄

Saliva: Chemical and Physical properties

  • clear liquid
  • comes from the mouth
  • helps break down food in the mouth
Photo by widdowquinn

Semen: Chemical and physical properties

  • sticky clear/white substance
  • Glows in UV or Black Light
Photo by staflo

Forensic science of body fluids

  • the presence of body fluids at a crime scene can indicate what type of crime occurred
  • for example if there is semen, a rape could have occurred
  • if there is blood there could have been an assault or even a murder
  • excreted fluids: feces, bile, vomit, and skin oil
  • Secreted fluids: blood, semen, and saliva
Photo by Mike Monteiro

forensic Scientists and body fluid

  • identify the fluid
  • example specific test to tell if it human or not
  • then run DNA tests on the items to see who it came from
Photo by garryknight

case study

  • April 22, 1993 Stephen Lawrence was murder outside a bus station in the UK
  • he was attacked by a group of 5-6 men and stabbed multiple times
  • originally there were 5 men arrested but the case went cold and no one was convicted
  • the case was reopened in 2006 due to the innovations in DNA technology.
  • microscopic blood stain was found and convicted Dobson and David Norris
Photo by fung.leo