Douglas describes the profiling process. During this process, he reviews a case in its entirety, examining crime scene photos, autopsy reports, witness statements, and other documents. After this initial review, he attempts to “put [himself] mentally and emotionally in the head of the offender” (147) in order to form a mental picture of the offender. From there, Douglas can assist local law enforcement in narrowing down the suspect pool.

The case of David Carpenter, the “Trailside Killer,” offers an example of this process. From August 1979 to May 1981, a number of bodies were discovered in the San Francisco Bay area on hiking trails in various state parks. The victims were all shot with a .38 or .44 caliber weapon. Special Agent Roy Hazelwood was originally contacted for assistance with the case, as he was widely considered an expert on rape and violence against women. However, Hazelwood had a full-time teaching load, and Douglas was the unit’s only full-time profiler, so he went to San Francisco to assist local law enforcement and the FBI’s San Francisco Field Office.

Marin County Sheriff G. Albert Howenstein, Jr. had contacted a psychologist, Dr. R. William Mathis, to consult on the case. After reviewing the case, Douglas challenged the profile of a charming handsome individual that Dr.