What is Forensic Science? Forensic Science A process based upon the SCIENTIFIC METHOD involving: 1 Analysis – studying an unknown item to determine its essential characteristics. – Ex: Fingerprints recovered at a C.S.
What is Forensic Science? Forensic Science A process based upon the SCIENTIFIC METHOD involving: 2 Comparison – examining how the characteristics compare with characteristics of known items. – Ex: Fingerprints on a recovered weapon
What is Forensic Science? Forensic Science A process based upon the SCIENTIFIC METHOD involving: 3 Evaluation – assessing the similarities and dissimilarities for identification purposes. =
What is Forensic Science? Forensic Science “FORENSIC” – (Latin): “Forensis”: public, public discussion, argument or debate.
What is Forensic Science? Forensic Science “FORENSIC” – characteristic of, or suitable for, a court of law.
What is Forensic Science? Forensic Science “FORENSIC SCIENCE” The application of scientific principles to any criminal investigation.
What is Forensic Science? Forensic Science Also sometimes called “Criminalistics”. A participant could be called either a “Forensic Scientist” or a “Criminalist”.
What is Criminalistics? Forensic Science “That profession and scientific discipline directed to the recognition, identification, individualization and evaluation of physical evidence by application of the natural sciences to law-science matters.”
Criminalistics Forensic Science “The science of Individualization” - no two things in nature are EXACTLY the same. - to demonstrate the uniqueness of an item of evidence.
EVIDENCE Forensic Science PERSONAL (eyewitness testimony) PHYSICAL (fingerprints) - very subjective & colored by personal attitudes & perceptions - very objective & remains the same for each observer.
Characteristics Forensic Science All NEW tires from the same mold show CLASS CHARACTERISTICS As a tire is used, it develops nicks and wear patterns that show INDIVIDUAL CHARACTERISTICS
Characteristics Forensic Science INDIVIDUAL CHARACTERISTICS allow a Criminalist to compare the Questioned Evidence (a tire tread imprint at a CS) to a Known Standard (a suspects tire)
INDIVIDUALIZATION Forensic Science Newcomb’s Rule: The probability of concurrence of all the separate events is equal to the continued product of the probabilities of all the separate events.” - Dr. Simon Newcomb
INDIVIDUALIZATION Forensic Science A questioned document shows... a typewriter to have 5 individual characteristics: (84 keys total) 1/84 x 1/84 x 1/84 x 1/84 x 1/84 Total probability of uniqueness is 1 out of 4.18 x 10 9 (~4 billion)
INDIVIDUALIZATION Forensic Science GOAL: to provide data that will show, in a court of law, that an item of evidence is in some way unique and may, in fact, be attributable to a unique individual & either help convict or exonerate that individual.
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