During World War II, the U.S. Army Signal Security Agency undertook an ambitious project, called Venona, to decipher the code the Soviet Union used to protect its diplomatic cables (messages transmitted by radio). Detection of a slight recurrence of code enabled cryptanalysts to eventually crack through several layers of cipher. The top-secret project revealed the names and activities of numerous Soviet spies, including British physicist Klaus Fuchs. In 1950, British authorities arrested Fuchs, who admitted he had passed on valuable information about the atomic bomb to the Soviet Union during World War II. Fuchs’s confession led to the identification of more spies, many of them Americans. One, Julius Rosenberg, was arrested by the FBI in June 1950. Rosenberg denied the charges of espionage. In January 1951, a federal grand jury indicted him and his wife, Ethel. Federal prosecutors announced their intent to seek the death penalty for the couple in hopes that Ethel, who did not directly take part in her husband’s spy work, would offer evidence against Julius. Both Rosenbergs, however, held firm in their assertion of innocence.

The Rosenbergs’ trial opened in March 1951 with Judge Irving Kaufman presiding. Ethel’s brother David Greenglass, who had also been charged with espionage, offered substantial testimony regarding Julius’s spy work and his sister’s knowledge of it. Prosecutors did not use the Venona cables because the U.S. government did not want the Soviets to learn that the United States had decrypted their wartime transmissions. Instead, prosecutors relied on Greenglass’s testimony, as well as that of another former spy, Elizabeth Bentley. Based on this evidence, the jury handed down a guilty verdict on March 29, 1951.

A few days later, Judge Kaufman sentenced the Rosenbergs to death. In this sentencing statement, Kaufman condemned the couple for betraying the United States.

Numerous appeals failed to overturn the verdict and sentence, which were controversial and prompted protests. The Rosenbergs had many defenders, who accused the federal government of framing the couple. President Dwight D. Eisenhower denied a last-minute appeal for a pardon, and on June 19, 1953, the Rosenbergs were executed. Neither ever admitted their guilt, but Soviet records have since confirmed that Julius spied for the Soviet Union and that his wife knew about this espionage.¹ Their deaths orphaned their two sons and added to the tensions in the United States brought by the fear of communism.