Crime Scene Investigation and Evidence Collection Chapter 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 cross transfer of physical evidence can occur

Part 2: states that the intensity, duration 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 trace evidence Pet hair on clothes or rugs Hair on brush Fingerprints on glass Soil tracked inside on shoes Drop of blood on t shirt A used facial tissue Paint chips Broken glass Fiber from clothing

Evidence Direct Circumstantial: firsthand 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, bullets, shell casings reduces number of suspects to group Biological : may make group of suspects very small or even one individual Body fluids, hair, plant parts, natural fibers

Individual evidence: single person, DNA, fingerprint, combination of unique traits Class evidence: narrows the identity to a group ex. Blood type ABO

Crime Scene Investigation Team: Police Officers: usually first (possibly a DA for a search warrant) Crime Scene Investigators: document crime and collect physical evidence= Recorder Sketch artist Photographers Evidence collectors Medical Examiners: aka: coroners 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 1.Securing the Scene 2.Separating the Witnesses 3.Scanning the Scene 4.Seeing the Scene 5.Sketching the Scene 6.Searching for Evidence 7.Securing and Collecting the Evidence

Securing the Scene First responding officer’s job #1 SAFETY #2 Preserve evidence –Protect area –Limit exchange –Request team

Separating the Witnesses 3rd priority; try to prevent collusion (creating a story) –Ask the following questions: When did the crime occur? Who called in the crime? Who is the victim? Can the perpetrator be identified? What did you see happen? Where were you when you observed the crime scene?

Scan the scene to determine what photos are needed –May determine primary (where a murder took place) and secondary crime scene (where the body was found)

Seeing the Scene Photos of overall area Close up photos with and without rulers Triangulation of stationary objects should be included in the photos as reference point View needs to be taken from several different angles and distances Several close up photos of evidence and bodies

 accurate rough sketch is made noting position of body if applicable and any other evidence All objects should be measured from 2 immovable landmarks Label N on the sketch and a scale Any objects within the vicinity of crime scene: windows, furniture, doors…. Outside; position of trees, vehicles, shrubs…. Make another final sketch for court Sketching the Scene:

Searching for Evidence Depends on number of investigators –Walk the scene marking location of evidence, photo, sketch –Single investigator: use grid, linear or spiral –Group: linear, zone or quadrant pattern –Patterns are systematic to ensure no area is left unsearched Additional light for hair / fibers Vacuum cleaner Flashlight and forceps reduce picking up extraneous

Securing & Collecting the Evidence Must be properly packaged, sealed and labeled –Specific procedures must be followed for collection and storage Liquids and arson remains = airtight, unbreakable container Biological evidence: breathable containers to reduce mold After evidence is allowed to dry then packaged into a paper bindle Paper bindle (druggist fold) then placed in paper or plastic container Outer container then sealed with tape and signed by the collector on the label

Evidence log and Chain of Custody document attached to the evidence container. Contains: –Case number –Item inventory number –Description of the evidence –Name of the suspect –Name of the victim –Date and Time of recovery –Signature of person recovering evidence –Signature of any witnesses present during collection

Crime Scene Reconstruction Hypothetical sequence of events – from before the crime was committed through its commission. Exam evidence and compare to witness accounts to determine reliability Evidence does not lie but it can be staged

Staged Crime Scenes Unique problem: evidence does not match testimony Common situations: Arson: stage fire to cover rubbery, murder Suicide/murder: death may be alcohol or overdose Burglary: staged to collect money

Things to consider when determining staging occurred Initially treat all death investigations as homicide Do the type(s) of wounds found on the victim match the weapon employed? Could the wounds be easily self inflicted? Establish a profile of the victim through interviews with friends and family Evaluate the behavior ( mood and actions) of the victim before the event Evaluate the behavior ( mood and actions) of any suspects before the event Corroborate statements with evidential facts Reconstruct the event Conduct all forensic examinations to determine the facts of the case

Jonbenet Ramsey iWnhT8https:// iWnhT8