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Evidence

Evidence. Forensics 3. Definition of Evidence. Anything legally submitted to a court of law that helps ascertain the truth of the matter under investigation The most important concept in criminalistics is identification (or individualization) of evidence. Purpose of Evidence.

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Evidence

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  1. Evidence Forensics 3

  2. Definition of Evidence • Anything legally submitted to a court of law that helps ascertain the truth of the matter under investigation • The most important concept in criminalistics is identification (or individualization) of evidence

  3. Purpose of Evidence • To connect or eliminate suspects • To develop or identify suspects • To develop or show a similar method of operation • To identify stolen items or illegal materials • To prove or disprove an alibi • To provide leads

  4. The “Holy Trinity” of Evidence • Physical evidence • Most important determinant in producing a conviction • Witnesses • Confessions • Without one of the first two in particular, it is very difficult to even find a suspect

  5. 4 Main Types of Evidence • Testimonial • Evidence presented by witnesses speaking under oath • Physical • Tangible objects found at a crime scene, etc. • Sometimes hidden to plain view and only becomes apparent after scientific processes…referred to as “latent” • Documentary • Video, sound or audio recordings • Demonstrative • Objects, etc. used to demonstrate or recreate a tangible event, place or object • Includes models, recreations, etc.

  6. Testimonial Evidence • People often remember more details from more severe crimes • Sex, hair color, ethnicity • “Reliable” witnesses • Children and elderly – often not reliable • Learning disabled, mental disabilities, drugs/alcohol • How was information gathered? • Open ended questions often yield best results • “Was the person’s shirt red?” – NO!

  7. Testimonial Evidence • Other Factors • Relation to people involved in crime • Fear • Prior incidents • Personal trauma

  8. Physical Evidence • Transient • Temporary, easily changed or lost • Pattern • Produced by direct contact • Conditional • Produced by a specific event or action • Transfer • Produced by contact between persons or objects • Associative • Items associated with a victim/suspect of scene

  9. Transient Evidence • Odors • Temperature • Imprints/indentations • Markings

  10. Pattern Evidence • Blood spatter • Glass fractures • Fire burn patterns • Ballistic trajectories • GSR • Body position • Tool marks

  11. Conditional Evidence • Lighting – Lighting conditions • Smoke – Color, direction of travel • Location of injuries, positions, debris • Vehicles – Doors locked/unlocked • Body – Position, rigor/livor mortis • Scene – Conditions/position of furniture

  12. Forensics and Evidence • Seven major activities in evidence use • Recognition • Preservation • Identification (scientific) • Comparison • Individualization • Interpretation • Reconstruction

  13. Legality of Evidence • Chain of Custody • Of highest importance to any investigation • Shows the unbroken sequence of events that is caused by an item of evidence from the time it is found at the crime scene to the time it appears in court • Every link must be documented from discovery, to gathering, storage, lab analysis, return to storage and transfer to court • Include dates, times, people involved and what was done to the evidence • If a constant chain can not be established, the evidence is worthless

  14. “Standards of Admissibility” • Vary from state to state, and sometimes from court to court within states • Relevancy test • Frye Standard • 1923 • In order for a scientific technique to be admissible, it must be “generally accepted” • Now superseded by Daubert Standard • Involved a polygraph test

  15. “Standards of Admissibility” • Coppolino Standard • 1968 • Allows for new types of tests to be used if adequate science exists • Marx Standard • 1975 • Courts do not have to sacrifice common sense when evaluating scientific evidence • Daubert Standard • 1993 • Court must decide on “expert” witnesses and general admissibility of evidence or techniques

  16. Evidence Concepts • Identity vs. Match • Identity is a set of characteristics by which something(body) is known. • Match is a set of characteristics that point to only one object/individual • Class vs. Individual • Class characteristics are common to a group of similar objects (e.g. Nike “swoosh”) • Individual characteristics are unique to one particular item or individual

  17. Science of Evidence • Locard’s Exchange Principle • States that each time an individual comes in contact with another, something of that individual is left behind while something of that place is taken away with the individual • Hair, skin flakes, dirt, etc. can all be used to link someone to a location • Evidence processing is expensive

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