Processing the Crime Scene

What is physical Evidence? Any and all objects that can establish that a crime has been committed OR Can provide a link between a crime , its victim or a crime and the perpetrator

What’s the first thing to do at a crime scene? 1. Secure and isolate crime scene 2. Record the scene 3. Conduct Systematic Search for Evidence 4. Collect and Package Physical Evidence 5. Maintain Chain of Custody

Secure and Isolate Crime Scene Responsibility of first officer on scene (take steps to preserve and protect scene) First priority - medical assistance Exclude all unauthorized personnel Establish and Control entry / exit points Ropes, Tape, Barricades and Guards strategically placed.

Once the scene is secure and lead investigator arrives – what happens? Boundaries of Scene determined Does the area being searched need to be expanded? Establish perpetrator’s path of entry and exit Obvious items photographed and documented Initial walk through to gain overview and develop strategy for systematic search

Name Three ways you could permanently record the scene: 1. Photograph 2. Sketch 3. Notes

Photography Crime scene should be photographed in its entirety. Where the crime happened and adjacent areas. Pictures of evidence to show location and position relative to entire scene. Close-ups to show injuries and physical evidence Measuring scale should always be included

Videotaping is also useful Long shots and close-ups Narration of events and scenes being videotaped can be useful for later analysis. Sights and sounds of crime scene can be recorded. Provides comparison to determine if scene has been altered or evidence moved during investigation. Still photography continues to be the preference for the majority of crime labs.

Sketches Once photographs have been taken, sketches are created. Investigator may not have time or skill so a ROUGH sketch is always created at scene. Finished sketch is finished after all data has been collected.

Notes Constant Activity throughout the process of investigating a scene. Notes must include: - detailed written description of the scene - Location of physical Evidence - Records time that each piece of evidence was discovered. - Record who discovered the evidence and how they packaged it Notes should be taken with great detail and in anticipation that this may be the only source of information for refreshing one’s memory after weeks, months or years of an investigation.

Search Search for physical evidence must be systematic and thorough. Type of search depends on size and location

Collect and Package Physical Evidence Physical evidence must be handled and processed in a way that prevents any change from the time it is removed to the time it arrives at the lab. What are some sources of contamination? Breakage Evaporation Accidental Scratching or bending Loss through improper Careless packaging

Chain of custody Continuity of possession Established when evidence is presented in court Info. Collected: initials, date,location of evidence To avoid confusion and retain control at all times – individuals on chain of custody should be kept to a minimum.

Removal of All evidence must be in accordance with appropriate search and seizure protocols.

2 Classifications of Evidence – used for comparison analysis Individual Characteristics Class Characteristics

Individual Characteristics Evidence that can be associated with a common source with an extremely high degree of probability. Examples: Fingerprints, striation marks on bullets, tool marks, footwear impressions, the comparison of handwriting characteristics, the fitting together of the irregular edges of broken objects (puzzle)

Class Characteristics Evidence that can only be associated with a group and never a single source. Most items of physical evidence retrieved at a crime scene cannot be linked definitively to a single person. Examples: Blood type, Layer of paint from a car, carpet fibers, etc…