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Chapter 2. The Crime Scene. Just like vehicles run on gas. Crime Labs "run" on . Physical Evidence. Physical Evidence. Any and all objects that can establish that a crime has been committed or can provide a link between a crime and its victims of a crime and its perpetrator.
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Chapter 2 The Crime Scene
Just like vehicles run on gas Crime Labs "run" on Physical Evidence
Physical Evidence Any and all objects that can establish that a crime has been committed or can provide a link between a crime and its victims of a crime and its perpetrator
Crime Labs do not solve crimes; only a thorough and complete investigation conducted by professional police officers will enhance the chances for the successful outcome of a criminal investigation
Forensic Science begins at the Crime Scene
Processing the Crime Scene 1. Secure and isolate the Crime Scene 2. Record the scene a. Photography – scene must be unaltered b. Sketches – rough vs. Final c. Notes – constant activity 3. Conduct systematic search for evidence
a. Physical evidence can be anything from massive objects to microscopic traces. 3. Search (continued) 4. Collect and Package physical evidence • Each different item or similar items collected at different locations must be place in separate containers • Packaging evidence separately prevents damage through contact and prevents cross-contamination (pg 44)
a. Continuity of possession 5. Maintain Chain of Custody 6. Obtain Standard/Reference samples • Standard/Reference samples • Buccal swab • Sustrate Controls 7. Submit evidence to the Laboratory 8. Crime Scene Safety
Legal Considerations at the Crime Scene Reasonable vs. Unreasonable Search and Seizures
"Reasonable" Must comply with the 4th amendment privileges (pg 50)
Justified Warrantless searches • Existence of emergency circumstances • Need to prevent the immediate loss of destruction of evidence • Search a person and property within the immediate control of the person provided it is made incident to a lawful arrest • Search made by consent of parties involved
Mincey vs. Arizona Petitioner's Claim That a search of his home conducted by police officers who did not first obtain a search warrant violated his Fourth Amendment protection against unreasonable searches, and therefore his criminal conviction based on evidence seized during the search was invalid. Decision That there is no "murder scene" exception to the requirement that police obtain a warrant before searching someone's home, and thus the appellant's conviction was invalid because it was based on evidence seized by the police during a warrantless search of his home. (pg 50)
Michigan vs. Tyler (pg 51) “We hold that an entry to fight a fire requires no warrant, and that once in the building, officials may remain there for a reasonable time to investigate the cause of the blaze. Therefore, additional entries to investigate the cause of the fire must be made pursuant to the warrant procedures.”
The message from the Supreme Court is clear: When time and circumstances permit, obtain a search warrant before investigation and retrieving physical evidence at the crime scene.