Crime Scene Analysis

How would a crime scene investigator handle the situations below.  Please include equipment that must be provided such as respirators and chemical suits or something as simple as gloves and masks. Discuss the manner in which officers should secure a crime scene after assuring public safety, and the policy for contacting other agencies.  Please provide references.

Chemical incidents
Fires
Contamination risks
Biological elements (blood, saliva, etc.)
Protective equipment for each hazard
Securing the crime scene to ensure public safety
A policy for contacting other agencies
Submit the project as a PowerPoint presentation