Allan H. Ryskind, here:
The FBI had opened a file on Oppenheimer as early as 1941, after he
had failed to immediately inform superiors that three men in Berkeley,
California, had been solicited to obtain nuclear secrets for the Soviet
Union and that both he and his brother Frank had been urged to help
them. One of his colleagues at the University of California at Berkeley
was Haakon Chevalier, who worked with Oppenheimer on various Communist
enterprises and who urged him to give Soviet Union Premier Josef Stalin
what he wanted.
The Bureau opened its file on Oppenheimer after he had attended a
December, 1940, meeting at Chevalier's home that was also attended by
the Communist Party's California state secretary William Schneiderman
and its treasurer Isaac Folkoff, each of whom was being wiretapped by
the FBI.
In early 1943, Chevalier had a brief conversation with Oppenheimer in
Chevalier's kitchen, with Chevalier mentioning that a scientist, George
Eltenton, could transmit information of a technical nature to the
Soviet Union about our progress on the highly secretive atomic bomb
project that Oppenheimer was working on.
He initially rejected the overture to assist Eltenton but failed to
report the incident until August of 1943. His failure to promptly report
what was clearly a Soviet espionage effort would become central to the
decision to revoke his security clearance. Oppenheimer did not report
the recruitment effort until six months later. In subsequent interviews
with Army security, he admitted he had been approached, but he refused
to name Chevalier or anyone else who might have been involved. Not until
December, 1943, in response to a direct order from Groves, did he name
Chevalier.
From 1937 to 1942, he was a member at Berkeley of what he called "a
discussion group," which was later identified by fellow members
Chevalier and Gordon Griffiths as a "closed" or "secret" unit of the
Communist Party for Berkeley faculty.