Familicide‐suicide following separation is under‐researched and remains a poorly understood phenomenon. Findings from previous research are inconclusive in relation to both risk factors and perpetrator motivation. This article explores the relevance of long‐term biopsychosocial antecedents in cases of familicide‐suicide that occurred in Western Australia between 1986 and 2005. A conceptualisation of the hypothesised risk factors in familicide‐suicide is proposed based on attachment theory, personality dysfunction, the neurobiology of trauma and the possible unconscious motivation of perpetrators, which may prove helpful in assessing the risk of familicide‐suicide in family court cases. The research identified and articulated a number of warning signs to familicide‐suicide that are often not identified, or appreciated, by decision makers. Suggestions are offered for changes to practice that may be helpful in identifying and responding to high‐risk cases in a way that enhances safety. Copyright © 2014 John Wiley & Sons, Ltd. ‘A conceptualisation of the hypothesised risk factors in familicide‐suicide is proposed’ Key Practitioner Messages Clinicians need to be aware of the dynamic psychosocial risk factors associated with violent acting out such as: The combination of Cluster B personality diagnoses. A history of domestic violence. Early childhood trauma requires good interagency communication and cooperation.