 Reimer was first investigated by American authorities in 1980 in connection with the John Demjanjuk case, but little progress was made during this initial investigation.Not until the fall of the Soviet Union and the end of Communism in the Eastern Bloc did investigators make substantial progress, as formerly restricted archives were opened up to Western historians.In 1992 the Office of Special Investigations filed a denaturalization suit against Reimer, and following a bench trial in 1998, Reimer was denaturalized on September 5, 2002.