** FILE ** In this 1951 file photo, Ethel and Julius Rosenberg are shown during their trial for espionage in New York City. Grand jury transcripts released Thursday from the biggest espionage case of the Cold War raise questions about whether Ethel Rosenberg was convicted and executed based on perjured prosecution testimony. The Rosenbergs were convicted of passing nuclear weapons secrets to the Soviet Union and were executed in 1953. Since then, decrypted Soviet cables have appeared to confirm that Julius Rosenberg was a spy, but doubts have remained about Ethel Rosenberg's role. (AP Photo/File)