The climax of the most sensational spy trial in American history is reached when a federal judge sentences Julius and Ethel Rosenberg to death for their roles in passing atomic secrets to the Soviets. Although the couple proclaimed their innocence, they were executed in June 1953.

The Rosenbergs were convicted of playing a central role in a spy ring that passed secret data concerning the atomic bomb to the Soviet Union during and immediately after World War II. Their part in the espionage came to light when British physicist Klaus Fuchs was arrested in Great Britain in early 1950. Under questioning, Fuchs admitted that he stole secret documents while he was working on the Manhattan Project—the top-secret U.S. program to build an atomic bomb during World War II. He implicated Harry Gold as a courier who delivered the documents to Soviet agents. Gold was arrested a short time later and informed on David Greenglass, who then pointed the finger at his sister and brother-in-law, Ethel and Julius Rosenberg. Julius was arrested in July and Ethel in August 1950. After a brief trial in March 1951, the Rosenbergs were found guilty of conspiracy to commit espionage. At their sentencing hearing in April, Federal Judge Irving R. Kaufman described their crime as “worse than murder” and charged, “By your betrayal you undoubtedly have altered the course of history to the disadvantage of our country.” He sentenced them to death.

READ MORE: Why Were the Rosenbergs Executed?

The Rosenbergs and their attorneys continued to plead their innocence, arguing that they were “victims of political hysteria.” Humanitarian organizations in the United States and around the world pleaded for leniency, particularly since the Rosenbergs were the parents of two young children. The pleas for special consideration were ignored, and Julius and Ethel Rosenberg were executed on June 19, 1953.