In an attempt to explain the relationship between psychopathy and severe violent behavior, this study associates previous animal abuse, psychopathy, and sadistic acting in forensic patients. Two topics are addressed: (i) whether previous animal abuse can be identified by a patient's Psychopathy Checklist profile and (ii) whether animal abuse statistically mediates between psychopathy and sadistic acting. In a German forensic hospital, 60 patients were investigated. Animal abuse was assessed using face-to-face interviews and the Psychopathy Checklist: Screening Version (PCL:SV), and sadistic acting was identified by file records.Discriminant analysis separated previous animal abuse (10/60) by high adolescent antisocial behavior, superficiality, lack of remorse, lack of empathy, and grandiosity. The mediation from psychopathy to sadistic acting (6/60) through animal abuse was found to be complete.The results, although sample size is limited and base rate of animal abuse and sadistic acting are low, fit with a model suggestive of animal abuse as a causal step toward sadistic crimes. Animal abuse correlates with callous, unemotional traits, and a development of sadistic crimes.