Who organized the Nuremberg trials?

During the Tripartite Dinner Meeting at the Tehran Conference, held from November 28 to December 1, 1943, Stalin proposed executing 50,000 - 100,000 Nazi staff officers. Churchill denounced the idea of "the cold blooded execution of soldiers who fought for their country" and that he'd rather be "taken out in the courtyard and shot" himself than to partake in any action. However, he also stated that war criminals must pay for their crimes and that in accordance with the Moscow Document which he himself had written, they should be tried at the places where the crimes were committed. Roosevelt had less sympathy for the remaining Nazi leaders.

The plan for the "Trial of European War Criminals" was drafted by US Secretary of War Henry L. Stimson and the War Department. Following Roosevelt's death in April 1945. The new president, Harry Truman endorsed the plan. After a series of negotiations between Britain, the US, Soviet Union and France, details of the trial were worked out. The trials were to commence on 20 November 1945, in the Bavarian city of Nuremberg.