How dark is the personality of murderers? Psychopathy, Machiavellianism, and sadism in homicide offenders

Dark personality traits describe amoral and antisocial behavioral dispositions and are often described by psychopathy (i.e., interpersonal, affective, lifestyle, and antisocial characteristics), narcissism, Machiavellianism, and sadism. These traits are related to various socially detrimental behavioral outcomes, including criminal behavior and delinquency. Furthermore, psychopathy is frequently related to homicide, both in scientific and in popular literature; however, the empirical data on the link between psychopathy and other dark traits with homicide is still scarce. We examined self-reported psychopathy, Machiavellianism, sadism, and the indicators of criminal recidivism (number of offences, number of lawful sentences and penal recidivism) in a sample of male homicide offenders (N = 46), other violent offenders (N = 82), and non-violent offenders (N = 119). The results showed that homicide offenders have less pronounced psychopathy, sadism, and criminal recidivism compared to the other two groups - the differences were particularly evident in comparison to the group of non-homicide violent offenders. There were no statistically significant differences in Machiavellianism. Our data cast a doubt on the widely acknowledged link between psychopathy and murder. The findings can be explained largely by the fact that homicide is a heterogeneous criminal offence; while it is possible that psychopathy and other dark traits may be linked to some types of homicide, this link cannot be established for homicide in general.