they could not find many of them- they hid their identities
They prosecuted the people they could prove were responsible. I dont think anyone would have considered the suggestion that any soldier associated with the camp in any capacity be prosecuted and charged with murder a serious proposal.
There was a family at my university, a professor and his son, a grad student TA, and only later was I told that they had come from Brazil. They had German surnames and were blond. Not Jewish either. People did wonder if they weren’t descended from Nazis. I didn’t get it at the time.