Psychopathy-associated personality traits influence crime-scene behavior in male homicide offenders.

We investigated whether psychopathy-associated personality traits and behavioral styles affect the manner in which homicides are committed or the motives underlying them. Using three nationwide registries and an in-house homicide database based on court verdicts, we identified all cases of homicide in Sweden during the years 2007, 2008 and 2009. In 72 male offenders who had undergone assessment using the Psychopathy Checklist - Revised (PCL-R), the manner of homicide was categorized as instrumental or expressive, and the motive as belonging to one of five categories: (1) intimate-partner or family-related homicide; (2) homicide occurring during altercations, (3) robberies or burglaries, or (4) criminal conflicts; or (5) sexual homicide. Offenders who had committed homicide in an instrumental manner or with a sexual motive had higher scores on PCL-R factor 1 than offenders displaying an expressive manner or other motives, suggesting that partially adaptive personality traits influence the crime-scene behavior of the former type of offenders more than maladaptive behavioral styles.