Testosterone and ruthless homicide

Prior studies have found higher levels of testosterone among persons who commit violent crimes than among those who commit nonviolent crimes. The present study examined data from 230 male prison inmates to determine how testosterone levels might relate specifically to the way in which inmates committed their crimes. Characteristics of inmate behavior associated with murder, manslaughter, robbery, assault, rape, and child molestation were scored from parole board investigative reports, and inmate testosterone levels were assayed from saliva samples. Among inmates who committed homicide, those high in testosterone more often knew their victims and planned their crimes ahead of time. Testosterone was not related to these characteristics for other violent crimes.