Gordon Mason, 57, was last seen at his San Francisco home on December 13, 1980, and has not been heard from since. He is described as 5 feet 10 inches, about 160 pounds, with gray hair and brown eyes. At the time he disappeared he was wearing tan slacks, a light-colored shirt and a tan raincoat.

Very few details have emerged over the years and investigators report no evidence indicating what happened to him. The San Francisco Police Department lists the case as an endangered missing person and has dental records on file, but no significant clues, suspects or leads have been reported.

Does anyone have information about where Gordon Mason lived, who he associated with, or any sightings around December 1980?