Go see this Weekly Standard article on Morton Sobell and the Rosenbergs: Ethel and Julius. If there was ever any lingering doubt about their guilt, this should erase it. These lovelies were committed supporters of the Soviet Union, active spies.
The information they passed along was used to kill American GIs in Korea. The Rosenbergs deserved what they got (death) and the rest of the ring should have gotten the same.