sentences:  These records, captured by the United States Army in May 1945, had been classified documents in the United States for several decades, and had been returned by the US National Archives to the German Bundesarchiv in 1975.De Zayas was head of a working group specialising in international humanitarian law, the "Arbeitsgruppe Kriegsvölkerrecht", at the Institute of International Law at the University of Göttingen.Together with a Dutch colleague from the University of Amsterdam, Walter Rabus, he undertook the evaluation of the recently declassified records, as well as related records of the Wehrmachtführungsstab, Fremde Heere Ost, and Kriegstagebücher (war diaries of army units).