GWINN (AP) — U.S. Air Force investigators say the remains of an airman who disappeared 40 years ago have been found near a former base in Marquette County.

The Air Force Office of Special Investigations said in a release Thursday the remains found in November 2017 were matched this past July to those of Sgt. Donald Rexroth. His remains were discovered near the former K.I. Sawyer Air Force Base, where he worked until May 1979.

Officials say foul play is suspected but they have unanswered questions. Rexroth’s relatives and friends told investigators he would not have left without saying goodbye.

The remains were logged into a missing persons’ database, and the Air Force’s Cold Case Team found they matched Rexroth’s age and height. Tests later matched DNA of the bones to relatives.