Based on research published on sexual homicide, one researcher identified two categories of offenders: compulsive sexual murderers and catathymic sexual murderers, each with distinct characteristics.
The compulsive sexual murderer is the least common type of sexual homicide offender. They typically leave an organized crime scene (see Table 9.1). That is, the crime scene indicates a certain degree of control was exerted over the victim, planning of the crime occurred, and little evidence is left behind. The sexual offense usually takes place prior to the victim's death. The offender's behavior is associated with an obsessive-compulsive pattern (Meloy, 2000).
The compulsive sexual murderer typically meets the diagnosis criteria of sexual sadism, deriving pleasure from inflicting harm on his victim. Either antisocial personality disorder or narcissistic personality disorder is usually present. Narcissism is usually present by exhibiting a sense of entitlement, grandiosity, and/or emotional detachment. Severe psychopathy is also common and often exhibited through their cruelty to others and predatory behavior. They are typically detached to other people. The autonomic nervous system, which controls such automatic responses as fight-or-flight and ability to relax, is typically underactive. This means that their responses to environmental stimuli (e.g., sudden, loud noises) are often dulled or non-existent. Early trauma is usually absent from their childhood histories (Meloy, 2000).
The catathymic sexual murderer—the most common of the two categories of sexual homicide offenders—typically leaves behind a disorganized crime scene (see Table 9.1), demonstrating a lack of planning of the homicide. The offender typically exhibits a mood disorder and a personality disorder. Their level of psychopathy diverges from the compulsive sexual murderer, in that mild to moderate psychopathy exists. They are often hyperactive and have a history of early childhood trauma (Meloy, 2000).