When recently widowed Jason Corbett hired a wholesome young American, Molly Martens, to care for his two young children, there was nothing to suggest she was a fantasist - and that her obsession with his children would end in his death.

In 2011, Jason and Molly married and settled in her native North Carolina. Just four years later, Jason was found beaten to death on the floor of the marital bedroom. The only others in the house were Jason's children, his wife and his parents-in-law. In a stunning twist, Molly and her father Tom, a former senior FBI agent, admitted to killing Jason but claimed self-defence, saying he had a record of domestic abuse.