Ellison was a student at Cedaredge High School, south of Cedaredge, Colorado on Highway 65, on February 10, 1981. He rode the bus to school as usual that day and the boy who shared his locker saw him place his books inside the locker at 8:30 a.m. Ellison did not attend classes that day and has not been heard from again. His mother told investigators her son carried only his wallet with his driver's license and three dollars inside it when he was last seen. He left behind all his clothing, his car, and money in his bank account.

Authorities suspect foul play was involved in Ellison's disappearance; they believe he was killed shortly after he vanished, probably by someone he knew. His mother says he had no reason to run away from home. He was a popular straight-A student at the time of his disappearance and had already been accepted at a college and selected a dormitory room. He was also an avid skier who was looking forward to an upcoming ski race which was held the weekend after he vanished.

Ellison's case remains unsolved. His psychology teacher was questioned in his disappearance but never charged. Both of his parents are now deceased.