http://www.brotherhoodofthebomb.com/bhbsource/authorsnotes.html The claim that Robert Oppenheimer was both a Communist and a spy has been made, most recently, in a book by journalists Jerrold and Leona Schecter. In an appendix to Sacred Secrets: How Soviet Intelligence Operations Changed American History, the Schecters reproduce an October 1944 NKVD document which appears to show that Oppenheimer was a valuable source for the Soviets as early as 1942, and that "he provided cooperation in access to the research for several of our tested sources including a relative of [American Communist Party chief] Comrade Browder."
This is, in fact, the second document to mention Oppenheimer that has emerged from purported KGB archives. Both of these documents, and an analysis, may be viewed by clicking on the "Documents" feature from the menu above. See Document Set #2: "Was Robert Oppenheimer a spy?" -Gregg Herken
Hmmmmmmmmmm ... interesting.