During the Holocaust, there were a number of war crimes happening on a regular basis. These were not held accountable until near the end of World War II, when this was the biggest conflict the world had ever known. It wasn't just about the punishment for Holocaust-related crimes, but for all crimes against humanity, crimes that violated the terms of war, and conspiracy to commit the crimes in the first place. The most notable punishment of war crimes from WWII happened at the Nuremburg Trials, which Hitler, Himmler, Goering, and others missed out on because they had committed suicide to avoid certain death and prosecution.
Nazism focused on the willingness to commit suicide rather than to accept defeat. This was very important during the Second World War and was something that Hitler spoke on during the invasion of Poland. It was win or die trying, but the death would be at their own hands, according to Nazi ideology. Most of the suicides of Nazi party members that occurred during the WWII era were seen as 'heroic' and glorified to a point where people often saw it as the only solution. While most saw this as the only option, and a proud one at that, it was usually the result of fear as to what would happen if they were caught and held accountable by opposing forces.
War crimes were usually punished by death during and after World War II. The most heinous criminals were subject to hanging, provided that they didn't end their lives before their death date arrived. The governments of the Allied forces joined together in 1942 to punish war criminals of the Second World War. These people were on trial and wanted for things like murder, enslavement, religious persecution, racial persecution, and other similar heinous crimes. Twelve of the 22 'major' war criminals were convicted and sentenced to death. Three were sentenced to life in prison and three more were acquitted.
There were 12 more trials at Nuremburg through 1949, which handled the war crimes of lesser known parties or those with less involvement, including physicians, German leaders, and industrialists who had committed offenses against peace, humanity, or other war crimes. Because of the scale of the Nazi party, many of the perpetrators have never been caught to be tried and punished. A great deal of Nazis simply went back to their lives in Germany without being noticed at the end of World War II and the search for war criminals is still ongoing.