The murder of Hannah Clarke and her three children by her former partner in February provoked widespread soul-searching about the lives lost to domestic violence in Australia. Some experts say that intimate partner murder is the most predictable type of homicide and that by searching for a pattern of behaviour known as coercive control we can saves lives. In this episode of Full Story, Clarke’s parents talk about Hannah’s relationship with her ex-partner and what they wish they had known about coercive control