Kirchhoff was last seen in his hometown of Waterloo, Iowa on February 5, 1978. He is missing under unusual circumstances and is believed to have been taken against his will; authorities think his disappearance may have been drug-related. He was employed as a lineman for the Chicago Northwestern Railroad but had been laid off weeks before his disappearance. Nonetheless, Kirchhoff had just purchased a new house and appeared to be in good spirits.

In 2003, authorities acting on a tip began searching a rural 12-acre farmstead between Fairbank and Denver, Iowa for evidence related to Kirchhoff's case. It was once owned by a Waterloo man, Lonson "Lonnie" Luloff, who faced life in prison for federal methamphetamine and weapons charges in 1994 but was released in 2000 after cutting a deal with prosecutors. Luloff is described by investigators as one of the biggest drug suppliers in the area. Authorities are not calling him a suspect in Kirchhoff's disappearance, however, and nothing was found in the search of his farm.

Another missing Iowa man, Richard Forsyth, may have been connected in some way to Kirchoff's disappearance. He paid cash for a Cadillac a week after Kirchhoff vanished, then disappeared himself in 1979. He is still missing and has not been conclusively linked to Kirchhoff's case. Both men's cases remain unsolved.