Borer was last seen walking to Mile Marker 82 on Parks Highway, eleven miles north of his hometown of Willow, Alaska on April 26, 1989, at approximately 5:00 p.m. He was evidently en route either to go to a friend's home, or to play at a sandbar at the nearby Kashwitna River, which was iced over. He has never been seen again and was missed at 7:00 p.m. that evening. There was no hole in the ice of the river to indicate he'd fallen in. The river is shallow, but has a swift current. Search dogs traced Borer's scent to Parks Highway, but there was no sign of him afterwards.

Borer was a first grader at Willow Elementary School at the time of his disappearance. His parents were separated at the time of his disappearance and he lived with his mother, three brothers and one sister. He is described as a very independent child who once hitchhiked 60 miles to Wasilla, Alaska. His case remains unsolved. For lack of evidence, police are treating it as an abduction.