Patricia ’Patty’ Ann Lilly was 43 when she disappeared from Bison Mountain in Pike National Forest, Colorado, on October 5, 1980. Originally from Delaware, she had moved to Colorado to be with a man she planned to marry. On the hike that day she was walking behind a 29-year-old companion from Woodland Park and vanished during the outing.

Patricia was well equipped for the trip, carrying a week’s worth of provisions, a sleeping bag, and warm clothing suited for nighttime temperatures that could fall into the 20s. A large search covered roughly 400 square miles around Bison Peak and nearby areas including Tarryall, Lost Park, and Lost Creek, but no trace of her was found and the official search was called off after more than a week. The Park County Sheriff’s Office suspected foul play, and the Canon City District Attorney’s Office even consulted a forensic psychic during the investigation.

Decades have passed with no significant breakthroughs and the Park County Sheriff’s Office continues to list her as missing. If anyone knew Patricia, her companion, or has information about hikes on Bison Mountain in October 1980, please come forward.