 Little evidence exists distinguishing individuals with suicidal ideation SI from those at risk for suicidal behaviour, illustrating the need for more comprehensive biomarkers for clinicians to guide their treatment approach and for new treatment avenues. Current theories of suicide have suggested the importance of an individuals capability for suicide in predicting suicide attempt or death. Building on this, Yovell and colleagues 2016 provided important preliminary data that the opioid system via buprenorphine affects suicide risk, but the neural mechanisms and their relationship to capability for suicide are unclear. The goal of the proposed research is to identify the neural opioid network underlying capability for suicide using functional magnetic resonance imaging fMRI in order to determine if it can be a target for identifying high-risk individuals and for intervention. 