Sobell maintained his innocence after
his incarceration, claiming that he had fled to Mexico only to escape persecution for his previous membership in the Communist Party and for having falsely taken an oath that he had never been a Communist in order to obtain employment with the government. In 1974, he published a book, On Doing Time, in which he again insisted that neither he nor the Rosenbergs had ever engaged in espionage. In interviews published in 2008 and 2010, however, Sobell admitted that he and Julius had spied for the Soviets, and he provided details of their activities.
David Greenglass, who spied for the Soviet Union while a U.S. Army soldier stationed at the atomic research facility at Los Alamos, New Mexico, implicated his sister, Ethel Rosenberg, and her husband, Julius, in the espionage conspiracy. After his release from prison, he lived anonymously, as his wife and children had already begun to do, in order to escape the notoriety he earned through his activities as a Communist spy and his role in sending the Rosenbergs to the electric chair.
The trial lasted nearly a month, finally ending on April 4 with convictions for all the defendants. The Rosenbergs were sentenced to death row on April 6. Sobell received a thirty-year sentence. Greenglass got fifteen years for his cooperation. Reportedly, the Rosenbergs were offered a deal in which their death sentences would be commuted in return for an admission of their guilt. They refused and were executed.