CRIME SCENE INVESTIGATION & EVIDENCE COLLECTION

CSI team and Crime lab

The Seven S’s of Cime Scene Investigation

Responsibilities of first officer Obtain medical assistance for anyone in need Arrest any perpetrators Exclude all unauthorized personnel Isolate the area Determine the boundaries of crime scene Entry and exit points of perpetrator Initial walk through Develop strategy for examining and documenting crime scene Determining primary and possible secondary crime scenes Document and photograph obvious evidence

Crime Scene Search Patterns

photographs Objects must NOT be removed until photographed from all angles If anything removed it should be noted and NOT be reintroduced Include photos of adjacent areas, close-ups of victim’s relative position in the scene and injuries If size is significant, a point of reference should be included in the photo Videotaping and narrating the crime scene can also be done

Scaled sketch of the crime scene http://vimeo.com/45223797

The Frye Standard Frye v. United States (1923) (polygraph test questioned) The Frye Standard Practical application:

Evidence Direct Evidence

Evidence Circumstantial (Indirect) Evidence Locard’s Exchange Principle Established by Dr. Edmond Locard

Physical evidence

Biological evidence

The Innocence Project Beginning in 1992, used DNA to examine post-conviction cases Faulty eyewitness identifications accounted for up to 87% of the wrongful convictions

Control Sample: Standard/reference sample: Substrate control:

Packaging evidence Create a clean paper and place evidence in the X position Put the bindle into a plastic or paper evidence bag affixing a seal over the opening Write your name on the seal

Chain of Custody Provides documentation of every person who has come into contact with the evidence A paper trail Demonstrates to the courts that the evidence that is being presented at trial is free of contamination, alteration, or substitution

Bagging the evidence Bag the evidence Add identification Seal it Sign it across the sealed edge Sign over to a lab technician Open bag on non-sealed edge Return items to the evidence bag Seal evidence bag in another bag Sign the evidence log

Never package wet evidence while wet Blood stained material should NOT be stored in airtight containers due to mold potential. Paper bags or wrapping paper used. Air dry clothes and place in individual separate bags Charred debris from fire is sealed in airtight containers

Facts result from collected evidence processed by the forensic lab Lead detective aims to see how facts fit into the crime scenario Lab results can show the reliability of witness accounts, establish identity of victim or suspects, show suspects innocence or link them with the crime.

Crime scene reconstruction Crime scene reconstruction involves:

Staging When lab results don’t match up with the testimony of witnesses Common examples: