The aim of this study was to compare the baseline characteristics (demographic, psychiatric-psychopathological and legal) among Greek forensic patients found not guilty by reason of insanity. The first step of this approach being differentiating patients who committed a criminal offense during their first psychotic episode from the ones who did so later in the course of their illness. All patients were hospitalized in the Department of Forensic Psychiatry (DFP) of the Psychiatric Hospital of Thessaloniki (PHT) from January 2015 to January 2020 and were examined in order to be included in the study. The final research sample consisted of 78 patients (70 identifying themselves as males and 8 identifying themselves as females) aged 18 and older, 21 of whom committed a criminal offense during their first psychotic episode (FEP, N = 21) and 57 did so later on in the course of their illness (Course, N = 57). Data were collected from multiple sources and several psychometric tools were used (Mini International Neuropsychiatric Interview-M.I.N·I, Positive And Negative Syndrome Scale-PANSS, Addiction Severity Index-ASI, CAGE Questionnaire, Hostility and Direction of Hostility Questionnaire-HDHQ, Global Assessment of Functioning-GAF and Aggression Questionnaire). Comparing the two groups (FEP vs. Course) we found that patients in FEP were younger, had experienced stressful life events in the last 24 months, committed more serious violent crimes, and more frequently attempted suicide after the crime. Their victims were usually members of their family. The main psychometric disparities between the two groups were found in the "Hostility" score of the Aggression questionnaire, and the items "Criticism of Others" and "Paranoid Hostility" of the HDHQ questionnaire, where patients in FEP scored lower. Patients in FEP scored significantly higher in items P1 (delusions), P4 (excitement), P6 (suspiciousness/persecution) and P7 (hostility) of the PANSS scale. No statistically significant differences were found between the two groups regarding their evaluation with the CAGE, ASI or GAF questionnaires. When comparing the patients' present scores in PANSS scale, the patients in FEP had lower total scores in the Positive and the General Psychopathology subscales. Both groups showed significant improvement during hospitalization in all scales (PANSS & GAF), except for the Negative Subscale of the PANSS scale. Through logistic regression analysis, we found that patients in FEP were younger, more likely to have recently experienced stressful life events and more likely to have assaulted a member of their family. Patients with higher scores in the "Hostility" subscale of the Aggression questionnaire were found to remain at risk for committing a crime during the course of their illness. These findings underline the need to design and develop specialized mental health services in order to identify and treat patients involved in violent crime in a timely and effective manner addressing their multiple needs.