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Evidence

Evidence. Civil vs. Criminal Law. Two Types of Evidence in Court. Direct Evidence = Eyewitness Testimony “I saw her do it!” “I heard him say it !” Eyewitness testimony is nonphysical evidence. Indirect Evidence = Physical Evidence

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Evidence

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  1. Evidence

  2. Civil vs. Criminal Law

  3. Two Types of Evidence in Court • Direct Evidence = Eyewitness Testimony • “I saw her do it!” “I heard him say it!” • Eyewitness testimony is nonphysical evidence. • Indirect Evidence = Physical Evidence • “The victim’s hair was found on the defendant’s clothing.” • “The defendant’s DNA was found at the crime scene.” • Evidence generated by criminal activity is real evidence.

  4. Direct Evidence • Pros: • Easy to understand • It appeals to our common sense • Cons: • Witnesses can be wrong • Witnesses can lie • Witnesses can be biased

  5. Indirect Evidence • Cons: • Science (and scientists) can be hard for juries (and even judges) to understand • If evidence isn’t collected or tested properly, the conclusions drawn from it can be wrong • If there is some evidence that isn’t collected or some test that isn’t performed, then the conclusions drawn from what was collected can be wrong

  6. Indirect Evidence • PRO: Physical Evidence can be analyzed scientifically • Science is not biased • Science is logical, not emotional • Science is repeatable and can be demonstrated to work again and again • Conclusions drawn from good science can be trusted

  7. How Physical Evidence Is Used • Identification: • Attempts to determine the identity of the evidence (especially if unknown evidence) to as high a degree of certainty as possible • Examples: • What did this hair come from? • When the fire spread, was the accelerant kerosene or gasoline? • Is this a blood stain? • What is this unknown fiber

  8. How Physical Evidence Is Used • Comparison: • Determines if two objects (the evidence and a standard) have a common origin (are made of the same materials, come from the same factory, were both at the crime scene, were both fired from the same weapon, etc)

  9. Class Evidence • Evidence that is not unique • Not used to identify a person • An examiner can only figure out if the evidence being analyzed belongs to a particular group • Examples: • Blood Type • Car Make and Model • Hair Color • Clothing fibers • Soils • Illegal drugs

  10. Individual Evidence • Evidence that connects to a specific individual • Unique • The evidence identifiesthe individual. • This piece of evidence can’t be linked to anyone else. • Examples: • DNA • Custom Paint on a Car • Fingerprints

  11. ORGANIZATION of aCRIME LABORATORY

  12. Physical Science Unit • Drugs • Identify the type of drugs • Glass • Particles being transferred from suspect to the crime scene or the crime scene to the suspect. • Glass containing bullet holes or other projectiles • Explosives • Identifies the explosive • Examines the charred remains of the explosion.

  13. Impressions • Markings from: • Tires • Shoes • Fabric • Teeth • Petroleum products • Accelerants in arson • Grease, oils found at the crime scene

  14. Plastic bags • Associated with homicides and drug cases • Identified with similar bags in the possession of a suspect. • Plastics, rubbers and other polymers • composition may be unique to a manufacturer. • Powder residue • Indicates firearm use.

  15. Soil and Minerals • link a person to a location • Vehicle lights • Lights at accidents are checked to see if they were being used • Fingerprints • Examination of visible, latent or plastic prints. • Serial Numbers • Identifies stolen property • Filed down or altered numbers can be recovered

  16. Biology Unit • Blood, Semen, Saliva: • Identifies individuals who may have been present at a crime scene. • Wood and vegetative matter • Wood, sawdust, shaving, leaves, flowers can link a person to an area. • Fibers • Natural or synthetic fibers that are transferred at the crime scene.

  17. Firearms Unit • Firearms & ammunition • Weapons • Ammunition • Casings • Bullet holes • Tool Marks • scrapes and scratches on a surface will match the tool that made it.

  18. Document Examination Unit • Documents: • Handwriting and typing • checks for authenticity of author • Inks and paper • checks for composition and age. • Related items, charred, burned or altered documents.

  19. Toxicology Unit • Organs & Physiological fluids • Detects drugs and poisons • Metabolic disorders

  20. Evidence Collection

  21. Specific Concerns for Vehicles • Cross contamination with another vehicle or person can transfer the following: • tissues • blood • hair • soil • paint • broken glass • fabric impressions • Evidence is located by: • Vacuums • Scraping • Visual examination of the area

  22. Specific Concerns forRape or Assault • Evidence from the Scene: • Broken glass • Blood • Weapons • Rope, tape • Victims clothing • Fingernail scrapings • Head and pubic hairs • Blood • Vaginal, anal and oral swabs • Recovered bullets

  23. Packaging Evidence • Each item must be packaged separately • Plastic pill bottles are useful for: • Hairs • Glass • Fibers • Other types of trace or small evidence • Manilla envelopes, glass vial or pill boxes are also useful • Specialized Containers are required for: • Bloody Clothes: Need to be placed in paper bags. • Arson Residue: Glass or metals containers with sealed lids.

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