secrets on behalf of the Soviet Union, by a person he did not know who worked for Shell Oil, and who had Communist connections. He gave that person's name as George Eltenton. When pressed on the issue in later interviews at Los Alamos in December 1943 with Groves, who promised to keep the identity of the three men from the FBI, Oppenheimer identified the contact who had approached him as Chevalier, and told Groves that only one person had been approached: his brother Frank. In any case, Groves had considered Oppenheimer too important to the ultimate Allied goals of building atomic bombs and winning the war to oust him over any suspicious behavior. He had ordered on July 20, 1943 that Oppenheimer be given a security clearance "without delay, irrespective of the information which you have concerning Mr. Oppenheimer. He is absolutely essential to the project." Oppenheimer was interviewed by the FBI on September 5, 1946. He related the "Chevalier incident", and he gave contradictory and equivocating statements, telling government agents that only he had been approached, by Chevalier, who at the time had supposedly said that he had a potential conduit through Eltenton for information which could be passed to the Soviets. Oppenheimer claimed to have invented the other contacts to conceal the identity of Chevalier, whose identity he believed would be immediately apparent if he named only one contact, but whom he believed to be innocent of any disloyalty. The 1943 fabrication and the shifting nature of his accounts figured prominently in the 1954 inquiry. The McMahon Act that established the Atomic Energy Commission (AEC) required all employees holding wartime security clearances issued by the Manhattan Project to be investigated by the FBI and re-certified. This provision had come in the wake of the February 16, 1946 announcement in Canada of the arrest of 22 people exposed as a consequence of the defection the previous September of Soviet cipher clerk Igor Gouzenko. President Harry S. Truman appointed Oppenheimer to the AEC General Advisory Committee (GAC) on December 10, 1946, so the FBI interviewed two dozen of Oppenheimer's associates, including Robert Bacher, Ernest Lawrence, Enrico Fermi and Robert Gordon Sproul. Groves and the Secretary of War Robert P. Patterson supplied written statements supporting Oppenheimer. AEC chairman David Lilienthal and Vannevar Bush discussed the matter with Truman's sympathetic aide Clark Clifford at the White House. They found John Lansdale, Jr.