Interview data indicate that while these men came from apparently stable, two-parent families, a majority had criminal, psychiatric, or substance abuse problems in their histories. Indicators of childhood and adolescent behavior problems were found among a large majority of subjects, including daydreaming, social isolation, masturbation, enuresis, rebelliousness, and chronic lying. Examination of early fantasy development of these men reveals a high degree of egocentricity in their negative, aggressive, and sexualized fantasy and play. Findings suggest that the murderers' early development of an active and aggressive fantasy life, combined with later sexual reinforcement and increasing detachment from social rules of conduct provide a framework that reinforces subsequent violent and sadistic behaviors. Results are discussed in terms of a five-phase motivational model that emphasizes the interrelationships among the murderer's ineffective social environment, formative events, patterned responses to these events, resultant actions toward others, and the killer's reactions via a mental feedback filter to his murderous acts. 47 references. (Author abstract modified)