Theodore Hall
Theodore Hall (October 20, 1925-1999) was an American physicist who leaked to the Russians a detailed description of the "Fat Man" plutonium bomb, and of the processes for purifying plutonium developed as part of the Manhattan Project. These secrets, combined with other information from other Soviet spies, are believed to have saved two to eight years for Soviet nuclear weapons program. Unbenknownst to Hall, Klaus Fuchs, a Los Alamos colleague, was also spying for the KGB; neither seems to have known of the other. Some of the their information provided an independent and confirming source for the other's. At only 19, Hall was the youngest scientist on the Manhattan Project. His wife would say, after his death that he had begun to develop strong feelings against the possibility of an emerging, militarized, United States, with a nuclear monopoly very early in his Los Alamos work.Hall, with the help of his college friend Saville Sax, who had open Communist sympathies, together visited New York, where Hall, after some searching, arranged a meeting with a Russian diplomat. He presented a detailed sketch of the Fat Man nuclear device to the official, who transmitted the information to the KGB from New York using the KGB's one-time pad cypher.
Until recently, nearly all of the severely damaging espionage regarding the Los Alamos nuclear weapons program was attributed to Klaus Fuchs. Hall was questioned by the FBI in 1951 but wasn't charged, for lack of evidence. Incredibly, despite having been infinitely more damaging to U.S. security than celebrated Soviet collaborators Harry Gold, David Greenglass, and Julius and Ethel Rosenberg, Hall was never imprisoned. It is claimed that Hall was not a Communist believer, but simply believed no nation should hold a nuclear monopoly. Eventually, Hall moved to Britain where he did important public research for the rest of his life.
Hall and his wife came under scrutiny in the early 1950's, but as with many cold war era spies, they went unpunished. This seems to have been primarily to keep secret the fact that the US has been partially successful in decrypting some messages carried in a Soviet one-time pad cypher (see Venona). The US seems to have also been more interested in securing existing projects than in any way jeopardizing several years of counter-espionage efforts.
For more on this, see Cold War espionage.
See Bombshell, by Albright and Kunstel for an account of Soviet espionage against the US during WWII, including background on Hall and his activities.
