Marianne Minor was 23 when she vanished from St. Thomas, Ontario, in late September 1984. At the time she was a resident of the St. Thomas Psychiatric Hospital; the last confirmed sighting was September 29, 1984, when she left her ward to go to the hospital’s canteen and never returned.

Very little else has been made public about Marianne or the circumstances of her disappearance. There are no widely reported witnesses to her leaving the hospital grounds and no known subsequent contact, which left the trail cold quickly and made the case difficult to investigate.