The Crime Lab

Crime Lab Structure Crime Scene Technicians are part of a larger organization called a Crime Lab. The crime lab includes all personnel associated with forensic examinations and evidence handling.

The Crime Lab Includes… Forensic chemists and biologist Latent fingerprint examiners Firearms and tool mark examiners Questioned document examiners Photographers Criminalsts Trace evidence specialists Administrative and support personnel

Crime Scene Technicians are just one part of a larger team that works together to process crime scenes and evidence.

Crime Scene Processing

Let’s get down to business.. Crime Scenes are chaotic. CSI is never the first to arrive at a scene. How does it all work?

Anatomy of a crime scene A crime occurs and is reported via 911. A patrol officer arrives and secures the scene. A patrol supervisor determines if the crime lab is required. The crime lab responds and takes control of the scene from the patrol officers. Detectives are dispatched to conduct the actual investigation of the crime.

Crime lab responds to… Homicides Suicides Suspicious Deaths Sex Offenses Domestic Assaults Felony Assaults Child Abuses Robberies Burglaries Arsons

Crime Lab does not respond to… Thefts Destruction of property (unless it is a hate crime) Auto accidents Accidental deaths

Processing a scene Is it safe? Body Substance Isolation (wear protective equipment always).

Scene Preservation Only authorized personnel may enter the scene. This minimizes contamination of evidence. The Transfer Theory states: “Everyone that enters a crime scene brings something in and takes something away”. Some evidence is fragile i.e.. Hairs and Fibers, Biological evidence, Latent prints, shoe wear impressions etc.

Documentation Nothing is moved until the scene is photographed and sketched. Evidence is collected one piece at a time to avoid contamination and mislabeling. Be thorough!

Crime Scene Sketches Are used to reconstruct the scene in court. Helps investigators and prosecutors get ‘The big picture”. Are done to scale. Are considered evidence.

2 types of sketches A rough sketch is done at the scene by hand. All measurements are done using the triangulation method. Sketches are always done after the evidence is photographed and before anything is moved. Must include compass bearing, temperature reading, exact time, weather and lighting conditions. The fire department and helicopters are sometimes used to provide light at large outdoor scenes in remote areas.

Rough sketch Done at the scene by CSI. Considered part of your scene notes and may be used in court. Is the basis for the CAD sketch.

Rough sketch A template is used to make the sketch.

CAD sketch Computer Assisted Design. Done with specific software programs. Very accurate. Can be done in 2 dimensional or 3 dimensional.

Examples of CAD sketches

Evidence Can be as small as a hair or as large as a truck. Is packaged according to departmental guidelines