Crime Scene Investigation and Evidence Collection ：犯罪现场调查和收集证据.pptVIP

Crime Scene Investigation and Evidence CollectionChapter 2  Goal to recognize, document and collect evidence at a crime scene Locard’s Principle Principle of Exchange Part 1: when a person comes into contact with an object or another person, a _____ transfer of physical evidence can occur Part 2: states that the intensity, _______ and nature of the materials in contact determine the extent of the transfer. Example: more transfer would occur after a fistfight, than a person simply brushed past another person. Locard’s Principle To a forensic examiner, these transferred materials constitute what is called ______ evidence Pet hair on clothes or rugs ______ on brush Fingerprints on glass Soil tracked inside on shoes Drop of ______ on t shirt A used facial tissue Paint chips Broken glass _____ from clothing Evidence Direct Circumstantial: _______ observations: eyewitness accounts dashboard video cameras confessions - used to imply but prove a fact - may link a suspect and a crime scene ex. Suspect’s gun found at crime scene Physical: Impressions, Fibers, weapons, _____, shell casings reduces number of suspects to group Biological : may make group of suspects very small or even one individual _______, hair, plant parts, natural fibers Individual evidence: single person, DNA, fingerprint, combination of _______ traits Class evidence: ________ the identity to a group ex. Blood type ABO Crime Scene Investigation Team: Police Officers: usually ________ (possibly a DA for a search warrant) Crime Scene Investigators: document crime and collect physical evidence= Recorder _____________ Photographers Evidence collectors Medical Examiners: aka: ________ may be necessary to determine cause of death in a homicide case Detectives: look for leads, interview witnesses and talking to the CSI about evidence Specialists: entomologists, psychologists may be required for evidence examination. 7 S’s of CSI