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3-2 Types of Physical Evidence

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1 3-2 Types of Physical Evidence
Unit 3: Physical Evidence October 26, 2014 Sanders

2 Types of Evidence Circumstantial evidence is evidence that relies on an inference to connect it to a conclusion of fact Scott Peterson had no physical evidence that linked him to the crime Direct evidence supports the truth of an accusation directly No need for any additional evidence or inference. September 1, 2019 Physical Evidence

3 "Locard's Exchange Principle"
Every time someone enters an environment, something is added to and removed from it. The principle is sometimes stated as “every contact leaves a trace”, and applies to contact between individuals as well as between individuals and a physical environment. Law enforcement investigators are therefore taught to always assume that physical evidence is left behind at every scene. This will be generally true, and the amount and nature of the evidence created will be largely dependent on the circumstances of the crime. September 1, 2019 Physical Evidence

4 Biological Evidence Biological crime scene evidence includes Blood
Semen Saliva DNA Hair Organs Physiologic fluids September 1, 2019 Physical Evidence

5 Impression Evidence Impression crime-scene evidence is material that includes Tire markings Glove/fabric marks Tool marks Bite marks Footprints Crime scene investigators from the Johnson County sheriff’s department photographed and took measurements of skid marks near 84th Terrace and Hallet Street in Lenexa. September 1, 2019 Physical Evidence

6 Manufactured Items Many common crime-scene evidence includes Firearms
Ammunition Fibers Paint Glass Petroleum products Plastic Plastic bags Rubber Polymers September 1, 2019 Physical Evidence

7 Blood, Semen, Saliva Materials may be found at crime scene.
Dried Liquid Subjected to serological biochemical analysis Cigarette butts, common source of saliva residue. September 1, 2019 Physical Evidence

8 Documents Any handwriting or typewritten document can be evaluated for authenticity. Paper Ink Burned or charred items. September 1, 2019 Physical Evidence

9 Drugs Any substance seized that is in violation of laws regarding controlled substances. Sale Manufacture Distribution Use of drugs September 1, 2019 Physical Evidence

10 Firearms The testing of firearms is called ballistics.
Ballistics compares spent ammunition. Size of residue left on gun shot indicates distance of fire. September 1, 2019 Physical Evidence


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