The study used a sample of 114 victim-defendant dyads composed of 100 unique male defendants charged with a deadly or dangerous crime against one or more persons. Three offense types predominated: homicides (n=43), endangerment (n=36), and battery (n=32). Information was obtained on the characteristics and criminal record of the defendant, descriptions of the criminal act and its context, the nature of the victim-defendant relationship, the precipitating events, the nature of the criminal interaction, and the history of mental health treatment. For the purposes of the study, "patient-defendant" included only those who had been assigned as an adult (18 or older) to an inpatient ward or to an outpatient program for treatment within 2 years of the initial court date in their criminal prosecution. Thirty-two victim-defendant dyads in the sample involved 30 unique defendants that fit this definition of patient-defendant. The analysis of the data used both multivariate and bivariate analyses of the conduct of the subjects. Where comparable, the findings from the study were in accord with the findings of other recent studies of crime and mental disorder. The comparison of patient-defendants with other defendants showed that the patient- defendants had a greater frequency of deadly and dangerous felony charges against them; however, the conduct of the patient- defendants was potentially and actually less harmful than their only-defendant counterparts, but more unpredictable. The patient-defendants were also less likely to attack strangers. 4 tables and 33 references