Chapter 2: Crime Scene Investigation & Evidence Collection

• to recognize • to document • collect evidence

Trace Evidence - can be found on both ppl (or objects) bc of the cross transfer Ex. hair, pet hair, paint, chemicals, soil/pollen, finger prints, etc.

• responsible for trace evidence • direction of the 1st forensic lab in France • Locard’s Exchange Principle

• a cross transfer of physical evidence occurs • the intensity, duration, and nature of the materials in contact determine the extent of the transfer

Direct Evidence Circumstantial Evidence

1st hand observations - eyewitness accounts - police dashboard cameras - confessions

Indirect used to imply a tact but doesn’t prove - provides 2 link between a crime scene and suspect - trace evidence is an example - 2 types

Physical and Biological

• all types of evidence exempt for fingerprints reduces the # of suspects to a small specific group of ppl Ex. fingerprints, footprints, shoe prints, tool marks, bullet shell casings

Any body fluids Ex. blood, saliva, vomit, etc

narrows an identity to a group of persons or things Ex. ABO blood type found at a crime excludes all other blood types

narrows down to a single person or thing

Police officers District Attorney Crime Scene Investigator Medical Examiner Detectives Specialists

1st to arrive

may be present if a search warrant is necessary

• sketch • record evidence • collect evidence • take pictures

coroner determines the cause of death

interviews witnesses & talks to investigators about the evidence

• expertise Ex. entomologists & forensic psychologists

• Secure the Scene • Separate the Witnesses • Scanning the Scene • Seeing the Scene • Sketching the Crime Scene • Searching for Evidence • Securing & Collecting Evidence

• done by the 1st responding officer • safety • preservation of evidence • prevent authorized ppl from entering the scene • keep a log of who enters the scene • may call for more help

• witnesses should not talk to each other • avoids a false story • when did the crime scene occur? • where were you? • who called 911?

• to determine where the photo should be taken • establish if there is a primary and secondary crime scene

location of the crime Ex. Nicole Simpson murder place