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Crime Scene Investigation and Evidence Collection

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Presentation on theme: "Crime Scene Investigation and Evidence Collection"— Presentation transcript:

1 Crime Scene Investigation and Evidence Collection

2 Lessons Learned Jon Benet Ramsey Case:
House not searched for 7 hours because assumption was that it was a kidnapping Only the girl’s bedroom was sealed initially Father found the body in the basement, wrapped her in a blanket and carried her upstairs After body was found, people allowed to move about freely in house House was cleaned

3 Chain of custody: Indicates every person who has handled the evidence
Log must be attached to packaging

4 Chain of Custody Essential to maintain
Original collector: bags evidence properly, labels it properly, seals it and signs the sealed edge. Next person to receive evidence signs that they received it (lab technician for example); lab tech opens sealed container at a location other than the sealed edge; after examination, tech repackages , signs log and reseals with new tape/signature.

5 Importance of Chain of Custody

6 Admissibility of Evidence:
Relevance Material -  The evidence must relate to the case at hand.  Previous criminal records are not material, and they can be prejudicial; as such, they are inadmissible. Probativeness - The evidence must prove something.  If the evidence, such as the possession of a poison by the accused, has no relevance to a death by strangulation, it is inadmissible.

7 Competence Constitutional Constraints - The 4th Amendment to the U.S. Constitution states the following: The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized. As such evidence obtained without a warrant, without probable cause, and not listed in the warrant as the place, person, or thing to be seized, is therefore inadmissible, regardless of relevance.

8 Competence Statutory Constraints - This is also called "Privileged Information," or information told to a person who cannot reveal it (such as lawyers or clergy). Hearsay - Hearsay is a statement made outside of court by a person who was not under oath when the statement was made, but is then being used as proof that the statement was truth. Prejudice - Anything that unduly affects the trier-of-fact in an opinion either for or against the accused, is considered prejudicial. Prior criminal records, or inflammatory images may therefore be ruled inadmissible.

9 Expert Witness: Forensic Evidence relies upon the testimony of expert witnesses. Expert witnesses are judged to be expert only by the Judge her/himself.  In order to be so judged, it is necessary to have the appropriate training and experience (which need not be a Ph.D.), as when a mechanic gives expert testimony regarding a car involved in an accident.  A non-expert witness is called a lay witness.

10 Expert Witness: Differences between an expert and a lay witness:
1. An Expert Witness must be qualified as an expert every time she/he testifies in court. 2. An expert witness is permitted to offer opinions, whereas a lay witness generally cannot.

11 Defense vs. Prosecution:
Innocent until proven guilty . . . Reasonable Doubt - The Prosecution has the burden of proof.  The defense has the responsibility to either exonerate the accused, or at least to introduce a reasonable doubt. Beyond a Reasonable Doubt vs. No Doubt (The jurors must decide . . .).  There is no precise definition, so it is thus in the hands of the jury. Defense must provide a spirited defense, regardless of the guilt or innocence of the accused (or a mistrial can be called).

12 Chain of Custody & Evidence Contamination:
The chain of custody, if not carefully managed, not only increases the risk of contamination, but it also can introduce a reasonable doubt. OJ Simpson & Oscar Pistorius:

13 OJ Debate You will either be arguing that the OJ Simpson Trial was fair, or, that he… got away with murder (pun intended). Read the article you get (there are 9 different ones) and take notes on your worksheet, building an argument for your side (you will be graded on this). Your group will convene for 15 minutes to discuss your side, plan an argument, and choose in what order you will debate. You will then have 15 minutes for a class debate. I will pick a winning side, that side will get 5 points extra credit.


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