As a group, the murderers were aware of their longstanding involvement and preferences for a very active fantasy life; they were devoted to violent sexual fantasies. Many also reported a history of sadistic behavior toward animals. Most fantasies prior to the first murder focused on killing. Fantasies that evolved after the murder focused on perfecting various phases of the murder. Some murderers were aware of their fantasy to rape and their motive to kill, but others described states of dysphoria such as being depressed or drinking heavily. One act of murder fulfilled the fantasy for some killers. Others felt compelled to continue killing, a need connected with their sense of control. The fantasy of the serial killer is vibrant and distinct from the other reality of the social world. The offender believes he can move from one reality to the other and that the ideas generated in fantasy are viable. These fantasies become so vivid that they provide the impetus for the offender to act them out with victims of opportunity. The fantasy underlying a sexually oriented murder drives the offender's actions through at least four major phases: planning and thinking about the murder; the murder itself, including gaining access to the victim and carrying out the crime; disposal of the body; and postcrime behavior. Discovery of the body is very important to the overall fantasy, and the murderer may even telephone or write to the police. Excerpts from the interviews are included.