For more than 30 years, retired Ontario Provincial Police Sergeant Barry Ruhl has believed that a criminal with whom he had a violent encounter early in his career might be responsible for a string of unsolved murders of young women in Ontario, including the 1959 death of 12-year-old Lynne Harper. The only suspect ever investigated in that sensational case was 14-year-old Steven Truscott, who was convicted and sentenced to hang before being cleared almost 50 years later. But in the 1980s, Ruhl had approached his superiors with a theory about an alternative suspect in the Harper murder and other similar cases. A Viable Suspect tells the story of how Ruhl arrived at his conclusions, his frustrated attempts to prompt the OPP to thoroughly investigate Talbot and the tragic irony of how, just when it seemed police were finally taking Ruhl's theory seriously, the suspect slipped out of reach, permanently.