Istvan Meszaros, The Power of Ideology, Harvester Wheatsheaf, London/NY, 1989, p118 on
The OSS was a branch of the FBI that became an independent service, the CIA. Marcuse started working for the OSS and was later employed by the CIA. All this is described in the first volume of Marcuse's papers (Technology, War and Fascism, ed Douglas Kellner).
I'm not convinced that talking down Marcuse's contribution to the American war effort as analysing German documents quite captures what it meant. Marcuse was advising the US government on the pacification of the German population under allied occupation. The content of the documents is largely along the lines of Lord Vansittart's 'collective guilt' thesis, adopted as US and later official German history after the war.
Given that the second world war was the period that saw the greatest expansion of US imperialism, I'm not sure that it is entirely excusable to work as a CIA agent.
But more than that Marcuse went on to analyse SOVIET society on behalf of the CIA. Taught Russian by the OSS he was invaluable in the analysis of Soviet documents and intelligence reports. At one point in the correspondence he complains that he is under pressure to identify the Soviet Union with Fascism (a pressure some would say he conceded to).
The reports and analyses that Marcuse prepared of Russian society were the basis of his later work, One Dimensional Man. -- Jim heartfield