Allister Mackenzie was 35 when he disappeared from Mill Valley, California, on October 3, 1977. He left his home that day and was never seen again. His car was later found abandoned on the Golden Gate Bridge in San Francisco, a detail that raised concern because of the bridge’s association with suicides, but no definitive evidence has established what happened to him.

Authorities classify Mackenzie as endangered and the investigation remains open. Decades of limited leads have left his whereabouts unresolved and no conclusive determination about his fate has been announced. Anyone who knew Mackenzie or who may have information about his activities in early October 1977 is asked to come forward.