Looking for information in my great grandfather, a member of the Ritchie Boys during WWII

My great grandpa's name was Walter Steene (Originally Steiner, but changed when he moved to the US, some records it appears as Steene or Steiner). A few years ago my family found out that he was part of the Ritchie Boys after seeing him in a photo of the 60 minutes special. I've been researching him for a while, and have found his name on some lists but have been unable to find much more. My grandma recalls him possibly doing some translation or interrogation during the Nuremberg Trials as well. There is also a possibility that he is linked to the discovery of Hans Frank's diary. (A Walter A Stein is mentioned in the footnotes of the Rise and Fall of the Third Reich, which my grandma discovered and believes to be her father). If anyone is able to help me find more records and information about Walter that would be great. I'm also happy to see anything about the discovery of Hans Frank's journal in general. Thank you!