4.1 Physical Evidence - lecture notes

4.1 Physical Evidence - lecture notes - YSCN0017 From...

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YSCN0017 From Sherlock Holmes to modern forensic science Physical Evidence It would be impossible to list all the objects that could conceivably be of importance to a crime. Almost anything can be physical evidence. It is practical, however, to list those items whose scientific examination is likely to yield significant results in ascertaining the nature and circumstances of a crime. Common Types of Physical Evidence Type of evidence Focused substances Example(s) in crime scene Test performed Blood, Semen and Saliva Liquid/dried, animal/human Fabrics with blood/semen; Cigarette butts containing saliva Serological and biological analysis Documents Handwriting and typewriting materials Paper, ink, indented writings, obliterations and burned/charred documents Drugs Any substance seized in violation of laws that regulate the sale, manufacture, distribution, and use of drugs Explosives Device containing an explosive charge Objects contain residues of explosive after an explosion Fibers Natural/synthetic fibers Clothing fiber of suspect/victim Fingerprints Latent/visible prints Firearms and Ammunition Firearm, discharged/intact ammunition Firearm suspected of being involved in a criminal offence Glass Glass particles/fragments Windowpanes containing holes made by a bullet Hair Hair of animal/human Detached hair found in crime scene Impressions All forms of tracks Tire markings, shoe prints, depressions in soft soils, bite marks in skin/foodstuffs and tool marks Organs and Physiological Fluids Body organs/fluids Metabolites of drugs/poisons, alcohol in body tissues/fluids Toxicological test Paint Liquid/dried paint Transfer of paint during an automobile collision Petroleum Products Residues of petroleum products Gasoline residues in the scene of arson Plastic, Rubber and Other Polymers Plastic bag involved in homicide Serial Numbers Restoration of erased identification numbers of stolen property Soil and Minerals Soil/minerals from a particular location Soil imbedded in shoes Wood and Other Vegetative Matter Fragments of plant Wood, sawdust, shavings / vegetative matter attached on clothing, shoes/tools
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p.2 The Examination of Physical Evidence The examination of physical evidence by a forensic scientist involves identification or comparison . Identification Identification is the process of determining a substance’s physical or chemical identity. Testing procedures that give characteristic results for specific standard materials are used. The number and type of tests must be sufficient to identify a substance and exclude all other substances unambiguously. There are no simple rules to define what constitutes a thorough and foolproof analytical scheme. Each type of evidence requires different tests, and each test has a different degree of specificity. Common identification tasks in a crime laboratory:
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4.1 Physical Evidence - lecture notes - YSCN0017 From...

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