This case report explores the diagnostic complexities and treatment challenges associated with psychopathy and antisocial personality disorder (ASPD) in a forensic psychiatric setting. Utilizing the Psychopathy Checklist-Revised (PCL-R) scale, we assessed a 29-year-old male previously detained for two attempted murders and investigated for insulting a public official. Despite a history of mood and psychotic symptoms, previous evaluations failed to identify underlying psychopathic traits. Our assessment revealed a PCL-R score of 33/40, indicating a clear picture of psychopathy. The subject exhibited aggressive and violent behaviors from childhood, including cruelty to animals and reckless actions. Diagnoses over time included attention deficit/hyperactivity disorder, bipolar disorder, and substance use disorders, reflecting significant diagnostic heterogeneity. The case underscores the importance of comprehensive psychopathy assessments in forensic contexts, particularly when previous diagnoses and treatments have been inconsistent. Our findings highlight the potential of the PCL-R scale as a valuable tool for identifying covert psychopathic traits, which are often underestimated. This study calls for further research into the diagnostic and therapeutic approaches for psychopathy and ASPD, emphasizing the need for tailored interventions in correctional institutions to mitigate the risk of recidivism.