William D. Sinclair, 29, of Hopkins, Minnesota, disappeared on April 28, 1978, after attending a party on 11th Avenue South near the Hopkins Police Department. His car was found abandoned nearby with the keys still in the ignition and his eyeglasses on the floor; there were no signs of him at the scene.

Sinclair was last seen wearing a blue jacket, a dark blue sweater, a light brown shirt, and blue jeans. He had a three- to four-inch surgical scar on his abdomen that could help with identification. Authorities list his disappearance as endangered, and searches have produced few leads.

His fate remains unknown and the case is unsolved. If anyone knew William, attended that party, or has information about his whereabouts, please come forward.