Peter Manuel was a Scottish serial killer who killed at least eight people between 1956 - 1958 around the Greater Glasgow area in Scotland. Manuel had prison for a string of sexual attacks but on his release it didn't take long for his psychopathic behaviour to escalate. He fell under the police's radar several times but each time was let go, free to kill further. Manuel's parents would always give their son an alibi. His father especially would go to great lengths to protect him from justice. When he was finally tracked down and arrested for the murder of a family, who he shot dead in their own home, Manuel sensationally defended himself in court. But it would be his mother's testimony which would prove to be crucial to the outcome.