Ackerman was last seen near Alton, Iowa on May 22, 2005, while on a fishing trip with his family. At the time, they were on a small cement bridge over Willow Creek. Ackerman's family lost sight of him for less than a minute between 3:00 and 4:00 p.m. and he disappeared. He is believed to have fallen into the creek and drowned, but an extensive search of the water turned up no sign of him or his remains.