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Understanding Forensic Characteristics of Evidence. Exploring Class Characteristics, Individual Characteristics, and Wear Characteristics. Class Characteristics.
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Understanding Forensic Characteristics of Evidence Exploring Class Characteristics, Individual Characteristics, and Wear Characteristics
Class Characteristics • Features shared by all members of a certain class or group of animals, plants, or other objectsand never with a single source. • Examples: • All human beings are biologically classified as Homo sapiens even though they look very different. • Sex traits can be used to characterize humans further into either male or female. • While class characteristics can be used to categorize individuals, they are not unique enough to individualize or associate items of physical evidence to a common origin.
Individual Characteristics • Properties of evidence that can be attributed to a common source with an extremely high degree of certainty. • Example: • If a piece of an item of clothing is missing and a piece of the same fabric matching the size and shape of the missing piece from the damaged garment is found in a suspect’s vehicle, one could state conclusively that the piece of fabric in question originated from the damaged article of clothing.
How could you describe these? Are these class or individual characteristics?
How could you describe these? Are these class or individual characteristics?
How could you describe these? Are these class or individual characteristics?
How do you know if something came from a common source? • You need a STANDARD/REFERENCE SAMPLE • Complete a COMPARISON ANALYSIS • A comparison analysis subjects a suspect specimen and a standard/reference sample to the same tests and examinations to see if they came from the same source. • Look for INDIVIDUALIZING CHARACTERISTICS • Wear Patterns: patterns caused by wear on footwear or tire treads • Accidental Markings: nicks and scratches by coming into contact with other surfaces, often on footwear or tire treads
Examples Class Evidence Individual Evidence