Dorothy Tate, 40, of Estes Park, Colo., was shot in the head while in her van, 2 1/2 miles north of Hearst Castle.
Her body was found Nov. 15, 1983.
Detectives then said their best lead was a camera stolen from Tate's van. A few years after the homicide, detectives were able to trace the camera to a pawn shop. However, none of the transactions associated with it led to an arrest.