Clifford Robert Olson Jr. was born on January 1, 1940, in Canada. Over nine months in 1981, he would become one of the country's most notorious serial killers—and the subject of one of its most ethically fraught criminal investigations.

Olson's killing spree began in April 1981 and accelerated dramatically that summer. His victims were children and teenagers, ranging from 9 to 18 years old. On April 16, he killed 13-year-old Colleen Marian Daignault. Six days later, 16-year-old Daryn Todd Johnsrude became his second victim. By late July, the body count had reached 11.

The murders were brutal. Some victims were strangled; others were raped and bludgeoned. Among the dead was Sigrun Arnd, an 18-year-old German tourist murdered on July 25. Nine-year-old Simon Partington, the youngest confirmed victim, was strangled on July 2. The pattern suggested a predator operating with increasing confidence and decreasing restraint.

Olson's criminal history offered little warning of what was to come. In 1976, while serving time for con artist crimes, he had worked as a prison informant. In 1978, he was briefly released from prison—an interval he used to sexually assault a 7-year-old girl. Later that year, while incarcerated in the Super Maximum Unit, he sexually attacked a 17-year-old inmate. By any measure, Olson was a dangerous man with a documented interest in sexual violence.