Donald Mackay was last seen outside the Griffith Hotel on July 15th, 1977 at about 6pm after he had been having a drink with some friends. Donald was a prominent anti drugs campaigner and it is believed he was murdered. An investigation of the scene where Mackay's locked van was parked revealed blood stains, car keys and three spent .22 shell casings.

Donald's body has never been located thus he is still a missing person.