In California in 1970, a doctor and his young family were executed and dumped in the swimming pool of their hilltop home. The killer believed that he was on a mission from God.
Featuring the killing of walkers in Yosemite National Park
Patrick Mackay is a British serial killer who confessed to murdering eleven people in the mid 1970s and considered by police to be a suspect in at least a dozen other killings over the previous two years.