Deetz was last seen on December 30, 1988. He was employed as a truck driver for Westside Transport in Cedar Rapids, Iowa at the time, and his last delivery was at the West Coast Grocery Co. Deetz called his employer from the Broadway Truck Stop in Spokane County, Washington on December 30, 1988, after he made his delivery. He also called his wife in Fullton, Illinois, to say he would be home soon. He has never been heard from again. Deetz's trucking supervisor reported him missing. His empty trailer was later found at the truck stop, and his truck, which was brand new in 1988 and worth $100,000, was found in the Los Angeles, California area in early 1991.

The truck was found on the property of Ralph Howard Benson, a self-employed long-distance trucker who traveled across the country. He was seen driving the truck, which he had repainted. The truck's license plate from 1988 was located in Benson's home. Authorities believe he operated a "chop shop," taking apart stolen tractor-trailer rigs and selling the parts. He was never charged in connection with Deetz or his vehicle, however. In 2003, Benson was convicted of murdering a Washington state auditor. Investigators stated he's a person of interest in Deetz's disappearance and other missing persons cases and homicides. He died in prison in 2004.

Deetz's supervisor reported him missing. He is described as a responsible man who was dedicated to his family and his job. He was carrying company credit cards at the time of his disappearance, but never used them. He left behind three children. He has since been declared legally dead and his wife has remarried. Foul play is suspected in his case, which remains unsolved.