David Greenglass

David Greenglass (March 2, 1922 – July 1, 2014) was an American machinist who worked on the Manhattan Project and was an atomic spy for the Soviet Union. He was briefly stationed at the Clinton Engineer Works uranium enrichment facility at Oak Ridge, Tennessee, and then worked at the Los Alamos Laboratory in New Mexico from August 1944 until February 1946.

He provided testimony that helped convict his sister and brother-in-law Ethel and Julius Rosenberg, who were executed for their spying activity. Greenglass served nine and a half years in prison.

Greenglass was born in 1922 on the Lower East Side of Manhattan in New York City, as the youngest of three children. His parents were Jewish immigrants Barnet "Barney" Greenglass (1875–1949), from Minsk, Russian Empire (modern-day Belarus), and Theresa "Tessie" Feit (1888–1958), from Kombornia, Austrian Galicia (modern-day Poland). He attended Haaren High School and graduated in 1940. He attended Brooklyn Polytechnic Institute but did not graduate.

Greenglass married Ruth Printz in 1942, when she was 18 years old. The two joined the Young Communist League shortly before Greenglass entered the U.S. Army in April 1943. They had a son and a daughter. He worked as a machinist at Fort Ord in California and then at the Mississippi Ordnance Plant in Jackson, Mississippi. In July 1944, Greenglass was assigned to the secret Manhattan Project, the wartime project to develop the first atomic weapons. He was first stationed at the Clinton Engineer Works uranium enrichment facility at Oak Ridge, Tennessee, but was there for less than two weeks. In August 1944 he was sent to the Los Alamos Laboratory in New Mexico. In order to pass his security clearance, he disguised or omitted details of his communist associations and had friends write glowing references.

Julius Rosenberg, who had married Greenglass' sister, Ethel, in 1939, had become an agent for the Soviet Union (USSR), working under Alexander Feklisov. In September 1944, Feklisov suggested to Rosenberg that he should consider recruiting his brother-in-law, David Greenglass, and his wife. On September 21, 1944, Feklisov reported to Moscow: "They are young, intelligent, capable, and politically developed people, strongly believing in the cause of communism and wishing to do their best to help our country as much as possible. They are undoubtedly devoted to us." David wrote to his wife, Ruth: "My darling, I most certainly will be glad to be part of the community project [espionage] that Julius and his friends [the Soviets] have in mind."

After Julius Rosenberg recommended his sister-in-law Ruth Greenglass to his NKVD superiors for the use of her apartment as a safe house for photography, the NKVD realized that David was working on the Manhattan Project. He was then recruited into Soviet espionage by Ruth at Rosenberg's behest in November 1944. Greenglass began to pass nuclear secrets to the USSR via the courier Harry Gold, and more directly with a Soviet official in New York City.

According to the Venona project intercepts decrypted by the National Security Agency between 1944 and some time in the 1970s, Greenglass and his wife Ruth were given code names. David was codenamed "KALIBR" (Cyrillic: Калибр, "calibre") and Ruth "OSA" (Cyrillic: оса, "wasp").

Greenglass turned down requests from the Los Alamos Laboratory (and Rosenberg) to work on the Operation Crossroads nuclear tests at Bikini Atoll because he wanted to be with Ruth. He was honorably discharged from the Army in February 1946. Greenglass returned to Manhattan, where, with his brother Bernie and Julius Rosenberg, he ran a small machine shop known as G & R Engineering.