On March 6, 1951, the espionage trial of Ethel and Julius Rosenberg began in New York. The couple was accused of selling nuclear secrets to the Soviet Union. The Rosenberg’s, and co-defendant, Morton Sobell, were defended by the father and son team of Emanuel and Alexander Bloch. The prosecution included Roy Cohn, best known for his association with Senator Joseph McCarthy. David Greenglass was a machinist at Los Alamos, where America developed the atomic bomb. Julius Rosenberg, his brother-in-law, was a member of the American Communist Party and was fired from his government job during the Red Scare. According to Greenglass, Rosenberg asked him to pass highly confidential instructions on making atomic weapons to the Soviet Union. These materials were transferred to the Russians by Harry Gold, an acquaintance of Greenglass. The Soviets exploded their first atomic bomb in September 1949 based on information Greenglass and other spies. The only direct evidence of the Rosenberg's involvement was the confession of Greenglass. The left-wing community believed that the Rosenberg’s were prosecuted because of their membership in the Communist Party. The trial lasted nearly a month, finally ending on April 4 with convictions for all the defendants. The Rosenberg’s were sentenced to death, while Sobell received a thirty-year sentence. Greenglass received fifteen years for his cooperation. Reportedly, the Rosenberg’s 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 in the electric chair at Sing Sing prison on June 19, 1953.