Dubbed by the media as "The Ken and Barbie Murders," the crimes of Paul Bernardo and Karla Homolka shocked the world in the early 1990s. The Toronto pair were young, attractive suburban newlyweds. Yet in some of the most gruesome crimes in Canadian history, Homolka helped Bernardo abduct, rape, torture, and kill teenaged girls, including her own 15-year-old sister. Bernardo, moreover, was revealed to be the notorious "Scarborough Rapist" named for the Toronto suburb where he preyed for years on women. The pair's trials in 1993 became a sensation because of the nature of these crimes and ongoing controversy over the graphic videotapes made of them.

Born in 1964, Bernardo was the youngest of three children in a troubled family marked by child sexual abuse, spousal violence, stalking, and infidelity. A junior accountant by day, he was a sexual sadist by night who bound and beat his girlfriends. By the...