Leading German officials were tried before the International Military Tribunal (IMT) in Nuremberg, Germany.
The IMT consisted of judges from Great Britain, France, the Soviet Union, and the United States. The overwhelming majority of post 1945 war crimes trials, however, involved lower-level officials and officers. Among them were concentration camp guards and commandants, police officers, members of the mobile killing squads, and doctors who participated in medical experiments.
These war criminals were tried by military courts in the British, American, French, and Soviet zones of occupied Germany and Austria; and in Italy. Others were tried by the courts of those countries where they had committed their crimes. Many war criminals were never brought to trial or punished.
Sources: United States Holocaust Museum