William Denson graduated from the US Military Academy at West Point in 1934 and attended Harvard Law School. He returned to West Point to teach law from 1942 until 1945. In January 1945, Denson accepted the position of Judge Advocate General (JAG) in Europe and was assigned to US Third Army headquarters in Germany. He took part in more than 90 trials against Germans who had committed atrocities against downed American pilots. In August 1945, Denson became chief prosecutor for the US government at the Dachau concentration camp war crimes trial. He was also asked to serve as chief prosecutor for a series of other concentration camp trials, including Mauthausen, Flossenbürg, and Buchenwald. These trials came to an end in early 1947, and Denson returned to the United States.
Now, we did get a lot of witnesses out of the DP [displaced persons] camps. Because those are the people that had no homes to go back to. They had been bombed out. Or their families had all been destroyed in the concentration camps. They had no place to go. So they were in these camps. And we took those people. And those that could make the best impression so far as credibility and knowledgeability were the ones that we used to make our cases.