When I was writing my book David and Goliath, I went to see a woman in Winnipeg by the name of Wilma Derksen. Thirty years before, her teenage daughter, Candace, had disappeared on her way home from school. The city had launched the largest manhunt in its history, and after a week, Candace’s body was found in a hut a quarter of a mile from the Derksen’s house. Her hands and feet had been bound.