I just finished "Operation Paperclip: The Secret Intelligence Program that Brought Nazi Scientists to America" by Annie Jacobsen. The title says most of it. I was aware of the rocket scientists, led by Wehrner Von Braun, who surrendered to the US Army a month before the end of WWII, and who were brought to America. But this book also tells, in detail, about the dozens of German chemical and biological warfare scientists, and "aviation medicine" specialists--many of them Nazi Party and SS members--who also were brought to the US. American authorities looked the other way at their horrible war crimes because the Soviets also got their share.

Leads me to this conclusion: The definition of a "Nazi war criminal" is a Nazi war criminal that neither the US or the USSR could use.