Due to the extreme secrecy of the Manhattan Project, espionage was always a main concern of the security force.  During the espionage investigation into the activities of British physicist, Klaus Fuchs, it came to the attention of the FBI that a member of the SED at Los Alamos had been passing classified documents relating to the atomic bomb to his sister and her husband.  What was the name of the SED member and who were the husband and wife team that received the secret information?