This from scribd is one.
http://www.scribd.com/doc/160228318/Communist-Attrocities-in-Buchenwald#scribd
Basically the nazis allowed the prisoners to set up a form of self governance inside the camp and control was promptly seized by the communists who proceeded to brutalize everyone else.
I think I heard about it from some captured American airmen on one of the history shows. They spoke of the communists attacking the nazi guards at the end of the war and driving them away only to continue running the show till the allies arrived a few days later.
Amazing story. No, funny that story never got out.