A Japanese researcher has found official U.S. documents detailing how the American military scattered the cremated remains of wartime Prime Minister Hideki Tojo and six other executed Class A war criminals in the Pacific Ocean, shedding light on the decadeslong mystery over their whereabouts.

The declassified documents, discovered by Hiroaki Takazawa, associate professor at Nihon University College of Industrial Technology, at the U.S. National Archives and Records Administration, contain a statement that a U.S. Army major "personally scattered the cremated remains" of the criminals over the Pacific Ocean.

It is the first time that details over the final disposition of the Class A criminals' remains have been found in official documents. While speculation and hearsay had circulated that their remains were scattered in the Pacific Ocean or Tokyo Bay, there had never been any official documents to back the claims.