A Brother's Betrayal In June of 1951, a husband and wife -- Julius and Ethel Rosenberg -- were executed in the United States. They had been convicted of passing atomic secrets to the Soviet Union. The star witness against them was Ethel's brother, David Greenglass. Greenglass also served 10 years in prison for spying. And then, he and his wife and children disappeared, into a fog of false identities. Decades later, New York Times reporter Sam Roberts tracked him down. Roberts recorded his conversations with Greenglass. Robert Siegel talks with Roberts about his encounters with Greenglass.