There is a new biography out on their American member.
Michael Straight is interesting for a bunch of reasons. Not the least of which is that he wrote an early anti-McCarthy book which was in all the best best bibliographies. His brother-in-law was one of McCarthy's "public cases" and the Straight connection was one of the reasons everyone knew Joe was wrong to accuse poor Gustavo Duran.
Then came his public confession (in the 1980s) that he had been recruited by the Soviets in the Thirties. (He maintained that he never spied on the US and that he had broken with Moscow by 1941).
Funny thing, people don't mention his McCarthy book much anymore.
From the reviews, it sounds as if the author has evidence that Straight did not break with Moscow as early as he said and that he did spy on his own country.
More on Duran:
For anti-anticommunists, McCarthy’s charges against Gustavo Duran stood as “proof of the insanity of the red scare.” Michael Straight, Duran’s brother-in-law and editor of The New Republic, would use the pages of his magazine to promote Duran’s supposed innocence and McCarthy’s assumed recklessness. Testimony by many attesting to Duran’s Stalinism and work for the Spanish Communist secret police during the Spanish Civil War—even a picture of him in a Communist uniform—was dismissed as Francoist propaganda. One would think that Straight’s later admission to being a Soviet agent should have at least sparked a second look into this McCarthy allegation by historians.