The cases that stunned Australia - and left us all with one question: Why did they do it?Peter Caruso bludgeoned his wife to death after almost fifty years of happy marriage. John Myles Sharpe killed his pregnant wife and their young daughter with a speargun. Katherine Knight stabbed and skinned her partner with the intention of serving his cooked carcass to his children. These and other crimes, committed by people described as average, ordinary, normal...In Why Did They Do It?, respected journalist Cheryl Critchley teams with esteemed psychologist Professor Helen McGrath to meticulously dissect the crimes, the evidence, the testimony, the confessions, and the overwhelming diagnostic evidence to analyse the minds and motivations behind crimes that shocked the nation.