Amy and her father, Marshall Midden, stopped at the Holiday Inn gasoline station in Osseo, Minnesota at 4:30 p.m. on August 5, 1989. They were on their way home from a day trip to the family farm at the time; they lived in Maple Grove, Minnesota. Midden went inside the station for a brief moment to use the bathroom. When he returned, he saw that she had disappeared from their parked vehicle. She has never been heard from again.

Authorities initially believed Amy ran away from home. She had been having some problems that summer and ran away repeatedly, but always returned home after a short time period. She is no longer classified as a runaway, however. It's possible that had a seizure while Midden was inside the building and became disoriented as a result. She may have walked away from their car afterwards.

Amy remains missing and her case is unsolved. Her family has kept the same telephone number since her disappearance in case she attempts to contact them. Her case received additional attention in the spring of 2014, after authorities searched her parents' farm and their residence in the 9700 block of Hemlock Lane north for information in her case, but the search turned up nothing of interest. Maple Grove police are investigating her disappearance.