Cpl David Mayes, the chief trainer for the military working dog section with PMO and a Johnstown, Pa., native and Xxerxes, his military working dog, conduct drug detection training at the Provost Marshal’s Office aboard Marine Corps Air Station Miramar, Calif., Dec 4. The dogs train to find the scent of drugs can differentiate the smells of several drugs. - Cpl David Mayes, the chief trainer for the military working dog section with PMO and a Johnstown, Pa., native and Xxerxes, his military working dog, conduct drug detection training at the Provost Marshal’s Office aboard Marine Corps Air Station Miramar, Calif., Dec 4. The dogs train to find the scent of drugs can differentiate the smells of several drugs.