The correct answer to this open question is the following.
The evidence that was brought forth during the trial to support the Nuremberg Trials indictments came from the thousands of documents that the allies found when Germany surrendered. Many witnesses wanted to give their testimony but just a few where heard. Judges mostly decided on the evidence found in the above-mentioned documents. The Nuremberg Trials were 13 trials in Nuremberg, Germany, held from 1945 to 1949. German military men and other civilians that helped the Nazi Party were found guilty of crimes against humanity.