The CIA historian published a CIA-vetted report, on CIA letterhead, that Clay Shaw was a "highly paid contract source" for the CIA in the 1950s.
IIRC, that wasn't the only mistake your boy, J. Kenneth McDonnald, made in that rushed-and-cobbled-together report.
Fred Litwin has written:
As for the document's reliability, researcher Paul Hoch has found another example of where it was wrong. It refers to "records relating to Gilberto Alvarado, who maintained that he witnessed Cubans passing Oswald cash at a party on the night before the assassination." In fact, this description is obviously a confused mashup of two allegations that were separately made: one by Gilberto Alvarado in 1963 (which he ultimately retracted), and another, made later, by Elena Garro de Paz. A different page in the 1992 document correctly describes Alvarado as "the Nicaraguan who claimed he saw Lee Harvey Oswald receive cash in meetings inside Mexico City Cuban embassy." Elena Garro de Paz claimed to have seen Oswald and two companions at a "twist party" in Mexico City. The date given for this twist party (November 21) matches neither allegation and is obviously an error, thus suggesting that the 1992 document is not a completely reliable accounting of what is in the CIA's own archive. On the night before the assassination, Oswald was in Dallas with Marina at Ruth Paine's house (thus he could not have received cash in Alvarado's presence or have been at a party in Mexico City). Oswald was only in Mexico City from September 26 to October 3. If he attended a party - which is a big if - it could only have happened during this time period.