Psychopathy continues to receive increased attention due to the negative outcomes, including recidivism, violence, and poor treatment amenability. Despite the vast amount of attention psychopathy has received, research on its applications to mentally disordered offenders remains sparse. The current study explored the relationship between psychopathy, depression, anxiety, and psychotic disorders. It also investigated the comparative fits of two and three-factor models of the PCL-R with mentally disordered offenders. Participants consisted of 96 inmates placed in the mental health pod at Tarrant County Jail. A Confirmatory Factor Analysis (CFA) with testlets found the three-factor PCL-R model had excellent fit (Robust Comparative Fit Index = 1.00). Psychopathy was found to be a construct independent of mental disorders. Two exceptions were (a) a modest correlation between anxiety and Impulsive and the Irresponsible Lifestyle factor of the PCL-R (r = 0.20) and (b) a modest negative correlation between Deficient Affective Experience of the PCL-R and mania (r = -.37). Based on the current data, treatment programs for mentally disordered offenders are suggested that focus on both behavioral and personality aspects of psychopathy.