People from bioenvironmental, the Air Force Office of Special Investigations, security forces and the fire department at Vance Air Force Base, Okla., walk a grid and mark evidence during an exercise April 15 on how to preserve and process a chemical or weapon of mass destruction scene that may be a result of criminal activity. The first responders received the training on how to process a hazardous materials incident from an AFOSI crime scene investigator. (Air Force photo/Capt. Tony Wickman)