Historians Harvey Klehr and John Earl Haynes Jr. have argued that CPUSA leaders (e.g., Earl Browder) doubled as either spies or spy recruiters, and they include Dirba among those. They state that Dirba used the codename "Lapin" and "K. Lapin" when sending messages to "Randolph" (which they deem a "generic pseudonym" for American representatives to the Comintern). Specifically, in VENONA document # 39, Lapin tells Randolph that "a food worker here in New York reports that he has overheard Solomon Rechter's brother boasting to somebody else that Solomon Rechter, in Moscow, was carrying on underground work for Zionist 'black shirts'–the Zhabotinsky group." The sender signed off "Comradely yours, K.Lapin, Sec.CCC"
