They included Theodore Hall, George Koval, Morton Sobell, David Greenglass, Julius and Ethel Rosenberg, Klaus Fuchs, and Harry Gold.
[7] During his stay in that city, they would have managed to be recruited by the GRU after looking for and contacting Morris Cohen,[8] an American who joined the Communist Party during the Great Depression[5] and worked as a Soviet spy.
By 1942, Perseus was supposedly already working at Los Alamos, being that they would have started sometime at least 18 months before German physicist and fellow atomic spy Klaus Fuchs, who joined the Manhattan Project in mid-1944.
"[8]In an interview published in 1992, the former Soviet consul in New York, Anatoli Yatskov, confirmed the existence of Perseus,[8] as an important figure among scientists working on the Manhattan Project.
[15] During his tenure as consul, Yatskov used the pseudonym Anatoly Yakovlev and served as a Soviet intelligence agent, coordinating atomic spies in the United States.
[8] The Venona project was a United States counterintelligence program run by the Signal Intelligence Service that (later became part of the National Security Agency,) started in the Second World War and was active since February 1943 to October 1980.
[16] The objective of the program was to intercept and decrypt messages from diplomats, intelligence agencies (such as the NKVD and the KGB), business representatives and other actors of the Soviet government.
[12] Despite the fact that by 2012 a publication by NSA's Center for Cryptologic History described PERS as "important, but still unidentified",[13] the references in the Venona files have been questioned[11] or even used to confirm that Perseus never existed.
[14] In 2009, VOGEL/PERS was outed as being actually Russell A. McNutt, a civil engineer employed by the company Kellex to work on facilities at Oak Ridge, who was recruited as a spy by Julius Rosenberg.
[23] After the dissolution of the Soviet Union, publications like those by Chikov and Yatskov strengthened the theory of a possible fourth spy in Los Alamos, who would have been identified as Perseus (the PERS in the Venona files) or FOGEL.
[26] American Cold War historian John Earl Haynes concluded that Perseus was an invention,[11] relying on the research of authors Joseph Albright, Marcia Kunstel and Gary Kern.
[7] According to historian John Earl Haynes and academic Harvey Klehr, thanks to FBI documents that were declassified in the 2010s, they were able to confirm the existence of a suspected fourth spy who they identified as Oscar Seborer.
[14] According to historian John Earl Haynes and academic Harvey Klehr, although Perseus never really existed,[14] some aspects of his character were based on or coincide with the American Soviet spy and physicist Theodore Hall.
[11] These aspects include: Born in New York City, Hall was an American physicist who was considered a prodigy from an early age, and graduated from Harvard University at 18.
Perseus loosely appears during the game's campaign and is featured in the final scenes of the Pro-Soviet ending as the one responsible for taking control of the fictional Operation Greenlight, which saw the insertion of nuclear weapons in every major European city, as an ultimate countermeasure to a Soviet invasion.