The incidence of psychopathy was between 15 percent to 30 percent of the selected population sample with a higher proportion present in the maximum security prisons. A Psychopathy Rating Scale developed by Hare and Frazelle divided the psychopaths into high, medium, and low psychopathy groups. In comparison to non-psychopaths, the psychopaths had a more extensive criminal history, committed more institutional offenses, and used more violence and threats during the infractions. A significant positive correlation was found between the degree of psychopathy and violation of parole, mandatory supervision, and incidents of unlawfully at large (UAL). Contrary to other reports, the persistent criminality of the psychopaths appears to extend well into their late 30s. 19 tables and 28 references (Author abstract modified)