Forensic psychology in Nigeria is a growing field, yet there remains limited understanding of psychological factors underpinning criminal behaviour. The study employed both qualitative interviews and quantitative surveys to gather data from forensic patients, staff, and community members. Quantitative findings were analysed using descriptive statistics, while thematic analysis was conducted on qualitative interview transcripts. Qualitative analysis revealed themes such as childhood trauma and social isolation, which contributed significantly to criminal behaviour among forensic patients. Surveys indicated that a quarter of respondents believed these factors warranted more comprehensive psychological support programmes. The mixed-methods approach effectively illuminated the multifaceted nature of psychological factors influencing criminal behaviour in Nigeria's forensic context. Based on findings, we recommend the development and implementation of targeted psychological interventions that address childhood trauma and social isolation among forensic patients.