Chapter 2 Crime Scene Investigation

goal of crime scene investigation recognize, document, and collect evidence at the scene of a crime Locard Exchange Principle Whenever two objects come into contact with one another, there is exchange of materials between them. Intensity, duration, and nature of materials determine the extent of transfer. Previous Play Next Rewind 10 seconds Move forward 10 seconds Unmute 0:00 / 0:15 Full screen Brainpower Read More Direct evidence eyewitness accounts, videos, confessions (first hand observations) Circumstantial evidence (indirect evidence) evidence used to imply a fact but not prove it directly Types of circumstantial evidence - physical - biological - trace Physical evidence Any object that can establish that a crime has been committed or can link a crime and its victim or its perpetrator. Biological evidence body fluids, hair, plant parts, natural fibers Trace evidence refers to physical evidence that is found in small but measurable amounts, such as strands of hair, fibers, or skin cells. Circumstantial evidence v. Direct evidence They are equal in the eyes of the law. The more circumstantial evidence there is, the greater weight it carries. Class evidence material that can be associated only with a group of items that share properties or characteristics Individual evidence a kind of evidence that identifies a particular person or thing Why Evidence is important Can prove a crime has been committed. Can back up witness testimony or prove it false. Can link a suspect with a victim or crime Determine the identify of people associated with a crime Allow investigators to reconstruct a crime Member of CSI First Responder Back up police - may district attorney Medics Investigators/Detectives Medical Examiner Photographer Field Evidence Technician Lab Experts Seven S's of Crime Scene Investigation (IN ORDER) Secure the Scene Separate the Witnesses Scan the Scene See the Scene Sketch the Scene Search the Evidence Secure and Collect Evidence Securing the Scene responsibility of the first-responding police officer (first responder), safety of individuals is first priority. Preservation of evidence is second priority. First responder has to restrict all unauthorized persons from entering. Locard's exchange principle may occur. -first responder keeps security log of all those who visit the crime scene -may call more teams of experts to sent to scene Separating the Witnesses Witnesses must not be allowed to talk to one another. This prevents them from working together to create a story (collusion). Sequential Presentation of line up members of line up are presented one by one; better way to increase accuracy of eyewitness identifications Simultaneous Presentation of Line up members of line up presented all at one time Composing the Lineup members of lineup should be selected based on their resemblance to the description provided by the eyewitness --- not the resemblance to the police suspect. Confidence Statement eyewitness statement (own words) that tells how confident they are in the identification of the suspect. Scan the Scene scan to see where photo