David Greenglass, the brother of Ethel Greenglass, was born in New York in 1922. He joined the Young Communist League (YCL). Greenglass married Ruth Printz, a fellow member of the YCL, in 1942. Later the couple had two children.
In 1945 Greenglass left the army and open a small machine shop in Manhattan with his brother-in-law, Julius Rosenberg. However, the business did badly and Greenglass left the partnership.
On 5th September 1945, Igor Gouzenko, a KGB intelligence officer based in Canada, defected to the West claiming he had evidence of an Soviet spy ring based in Britain. Gouzenko provided evidence that led to the arrest of 22 local agents and 15 Soviet spies in Canada. Some of this information from Gouzenko resulted in Klaus Fuchs being interviewed by MI5. Fuchs denied any involvement in espionage and the intelligence services did not have enough evidence to have him arrested and charged with spying. However, after repeated interviews with Jim Skardon he eventually confessed on 23rd January 1950 to passing information to the Soviet Union . Six weeks later Fuchs was sentenced to 14 years in prison.
In June 1950 the FBI arrested Harry Gold, who confessed to helping Klaus Fuchs in his espionage activities in the United States. He named David Greenglass as being a member of the spy ring. In July Greenglass was arrested by the FBI and accused of spying for the Soviet Union. Under questioning, he admitted acting as a spy and named Julius Rosenberg as one of his contacts. He denied that his sister, Ethel Rosenberg, had been involved but confessed that his wife, Ruth Greenglass, had been used as a courier.
Julius Rosenberg was arrested but refused to implicate anybody else in spying for the Soviet Union. Joseph McCarthy had just launched his attack on a so-called group of communists based in Washington. The head of the FBI, J. Edgar Hoover, saw the arrest of Rosenberg as a means of getting good publicity for the FBI. Hoover sent a memorandum to the US attorney general Howard McGrath saying: "There is no question that if Julius Rosenberg would furnish details of his extensive espionage activities it would be possible to proceed against other individuals. Proceeding against his wife might serve as a lever in these matters."
Hoover ordered the arrest of Ethel Rosenberg and her two children were taken into care. Julius and Ethel were put under pressure to incriminate others involved in the spy ring. Neither offered any further information.
Ten days before the start of the trial of the Rosenbergs the FBI re-interviewed David Greenglass. He was offered a deal if he provided information against Ethel Rosenberg. This included a promise not to charge Ruth Greenglass with being a member of the spy ring. Greenglass now changed his story. In his original statement, he said that he handed over atomic information to Julius Rosenberg on a street corner in New York. In his new interview, Greenglass claimed that the handover had taken place in the living room of the Rosenberg's New York flat.
In her FBI interview Ruth Greenglass argued that "Julius then took the info into the bathroom and read it, and when he came out he told (Ethel) she had to type this info immediately. Ethel then sat down at the typewriter... and proceeded to type info which David had given to Julius".
The trial of Ethel Rosenberg and Julius Rosenberg began on 6th March 1951. David Greenglass was questioned by the chief prosecutor assistant, Roy Cohn. After Greenglass testified to his passing sketches of a high explosive lens mold he provided incriminating detail of the Rosenberg's espionage activity.
Ruth Greenglass testified as to how she was asked by Julius Rosenberg to inquire of her husband, recently stationed in Los Alamos, whether he would be willing to provide information on the progress of the Manhattan Project. She also testified that Ethel Rosenberg spent a January evening in 1945 typing her husband's handwritten notes from Los Alamos.
The Rosenberg's defense attorney, Emanuel Bloch, argued that Greenglass was lying in order to gain revenge because he blamed Rosenberg for their failed business venture and to get a lighter sentence for himself.
In his summation, the chief prosecutor, Irving Saypol, declared: "This description of the atom bomb, destined for delivery to the Soviet Union, was typed up by the defendant Ethel Rosenberg that afternoon at her apartment at 10 Monroe Street. Just so had she, on countless other occasions, sat at that typewriter and struck the keys, blow by blow, against her own country in the interests of the Soviets."
Julius Rosenberg and Ethel Rosenberg were sentenced to death and remained on death row for twenty-six months. They both refused to confess and provide evidence against others and they were eventually executed on 19th June, 1953. As one political commentator pointed out, they died because they refused to confess and name others.
As a reward for his co-operation, Greenglass was only sentenced to 15 years in prison. He was released after only serving ten years. Greenglass went to live with his wife in the New York area under an assumed name.
In December 2001, Sam Roberts, a New York Times reporter, traced David Greenglass, who was living under an assumed name with Ruth Greenglass. Interviewed on television under a heavy disguise, he acknowledged that his and his wife's court statements had been untrue. "Julius asked me to write up some stuff, which I did, and then he had it typed. I don't know who typed it, frankly. And to this day I can't even remember that the typing took place. But somebody typed it. Now I'm not sure who it was and I don't even think it was done while we were there."
David Greenglass said he had no regrets about his testimony that resulted in the execution of Ethel Rosenberg. "As a spy who turned his family in, I don't care. I sleep very well. I would not sacrifice my wife and my children for my sister... You know, I seldom use the word sister anymore; I've just wiped it out of my mind. My wife put her in it. So what am I going to do, call my wife a liar? My wife is my wife... My wife says, 'Look, we're still alive'."