Who does what

Crime laboratories are dependant upon physical evidence in order to run

Physical evidence is any and all objects that can establish that a crime has been committed or that can create a link between a crime and a victim, or a crime and the perpetrator.

For physical evidence to be effective in aiding the investigation, it must…◦ Be recognized at the

crime scene◦ Be selectively collected

and Analyzed by experts in the field

If all physical evidence was collected and processed then the sheer volume of material would bog down the lab…so it is important to choose wisely

Securing and isolation of the crime scene is the responsibility of the first officer arriving on the scene

First priority does go to any individuals needing medical attention.

Priority then switches to the perpetrator if he/she remains at the scene.

Extensive efforts must be given to exclude all unauthorized personnel from the scene

Ropes, barricades, police tape, and strategically positioned guards are commonly used to prevent unauthorized access.

Why must crime scenes be isolated?◦ Remember Locard’s exchange principle

The officer charged with responsibility has the authority to exclude everyone, including fellow law enforcement officers, who is not directly linked to processing or conducting the investigation

The lead investigator starts the process of evaluating the area by making an initial walk-through of the scene.

At this point a strategy is developed for the examination and documentation of the crime scene