On 8 August, 1942, Riegner sent telegrams via British and American diplomats in Geneva to the Foreign Office in London and the US State Department. Riegner’s message stated that he had received an “alarming report” that the Nazis would exterminate the Jews “at one blow“, and that the action was due to start in the autumn of 1942 with the use of prussic acid (potassium cyanide/ Zyklon B). Riegner’s telegrams were among the first attempts to inform the allied governments about the Holocaust. These warnings were initially ignored by the Allies. One of Riegner’s sources of information for the telegrams was the German industrialist Eduard Schulte, Chief Executive Officer at the Silesian mining company Giesche. Through his work Schulte had various highlevel contacts with NSDAP and SS-officials.