Ruth Printz was born in 1925 and grew up in the same New York City neighborhood as David Greenglass. In late November 1942, Ruth married David Greenglass. Although both were still young, they wanted to marry before David was drafted. Both Ruth and David had an interest in politics and together they joined the Young Communist League.
The couple had not been married long before David was drafted in 1943. The two had always been a close couple and Ruth tried to see David as much as possible even after he had been inducted into the Army. In November 1944, Ruth left New York to visit her husband in Albuquerque, New Mexico while he was working as a machinist on the Manhattan Project at Los Alamos. It was during this visit that Ruth asked David to forward any information on the project to Julius Rosenberg, David's brother-in-law.
When the FBI questioned David Greenglass about suspected espionage activities, he agreed to confess and to be a witness against Julius and Ethel Rosenberg in exchange for immunity for Ruth so that she could remain at home with their two children. Ruth testified against the Rosenbergs at trial. Ruth testified that Ethel Rosenberg had typed up the notes that David Greenglass had provided, implicating Ethel in the espionage ring. Ruth also testified that it was Julius and Ethel who urged her to convince David Greenglass to become involved is espionage. Ruth rejoined with her husband after his release from prison.