Mary Jean Sylvestre, 37, vanished on September 11, 1977, while moose hunting with three friends in the Granite Creek area near Palmer, Alaska. The group was about six miles past Sutton when they tried to cross a rushing creek on horseback and Mary was thrown from her horse into the powerful current. Companions watched as the water swept her downstream and she disappeared from sight.

She was living on Buffalo Mine Road between Palmer and Sutton and was described as an experienced outdoorsperson. At the time she vanished she wore a wool jacket, a red and black plaid flannel shirt over an orange shirt, jeans with leather chaps, heavy socks, brown boots, and a gold wedding band on her left finger. The Alaska State Troopers filed a report the day after she was last seen and an extensive search failed to locate her.

Her disappearance has been treated as a suspected accidental drowning in difficult, remote terrain; her body was never recovered and the case remains open. Did anyone in the area at the time or who hunted Granite Creek later have information that could shed light on what happened?