Complex sentence: Saypol quickly advanced in the United States Attorney's Office, and in 1950-1951 he was Chief Prosecutor for the federal government in the espionage case against Julius and Ethel Rosenberg and Morton Sobell.
Split into simpler sentences: Saypol quickly advanced in the United States Attorney's Office. In 1950-1951 he was Chief Prosecutor for the federal government in the espionage case against Julius and Ethel Rosenberg and Morton Sobell.