PRE-PRINT VERSION OF PAPER To, W.T., Vandevelde, S., Soyez, V., De Smet, S., Boers, A. & Vanheule, S. (2012). Treatment Perspectives on Interned Mentally Ill Offenders in a Forensic Psychiatric Center (FPC): A Delphi Study on Experts' Opinions. Psychology, Crime & Law, doi: 10.1080/1068316X.2012.736511. Treatment Perspectives on Interned Mentally Ill Offenders in a Forensic Psychiatric Centre (FPC): A Delphi Study on Experts’ Opinions The study aims to map the treatment perspectives of international experts on treating mentally ill offenders in a Forensic Psychiatric Centre using the Delphi method. The four-round Delphi study reveals high conformity on the proposed treatment-related issues. However, some points of divergence remain. Three controversies underpinning these disagreements are discussed. The first controversy regards the treatment and control debate. The second controversy concerns the dual role of assessment in forensic mental health. The third controversy describes the potential entry conditions for treatment in a Forensic Psychiatric Centre. Further research is needed to scientifically underpin the above mentioned debates. In this regard, the study suggests a close collaboration between practitioners and researchers. Keywords: Mentally ill offenders; treatment; forensic psychiatric centre: delphi method Introduction Recently, there has been an increasing interest in the precarious situation of mentally ill offenders (MIO). A disproportionately high number of people with mental disorders has been reported in prison populations (Andersen, 2004; Black, Arndt, Hale, &