Beginning of the pursuit of war criminals in the Nazi era.

 After World War II, millions of refugees were born in Europe. Most were victims of the Nazi's, survivors of concentration camps, slave workers, prisoners of war, and those forced to migrate by the Nazi's. Western Europe, the United States, Canada, and Australia, which enjoyed relatively political and social stability, had no choice but to accommodate them, with nearly 1 million refugees supported by the International Refugee Organization (IRO), about 70% of which flowed into the United States, Australia, Canada, and the United Kingdom. However, these included Nazi officials who carried out genocide and punishment and those who voluntarily supported them. They disguised themselves as refugees from the Nazi and communist bloc by concealing their status and activities during the war. As their country became communist and unable to return, they moved to the United States, Canada and Australia, not to mention Western Europe. Among those who took refuge in Western countries disguised as refugees, there were not a few German residents of Eastern countries such as Yugoslavia, Romania, Czechoslovakia, Ukraine, the Baltic States, and Poland, and they gave active support and cooperation to Nazi war agencies. In this way, it is not easy for Nazi war criminals and inhumane criminals who have been hiding in shelters around the world to even check the exact number. According to officials from the Nazi-hunting organization, West Germany, and the U.S. government, the number of Germans responsible for inhumane crimes during and before World War II ranges from 150,000 to 200,000. After the end of the war, 35,000 Nazi criminals were prosecuted and executed by the United States and other allied countries, but this accounted for only 20% of all criminals, and the rest were scattered around the world in search of shelter. At that time, it was virtually impossible to classify and exclude those mixed with ordinary refugees. Even the IRO of the United Nations could not properly identify the refugees receiving the support. There could not have been a proper way to identify them on the ruins of war. Through this poor classification and examination, Nazi criminals were able to hide their past and safely seek refuge in a new country.