[Fedora]

Yes, Levison, and also Hunter Pitts "Jack" O'Dell, later foreign policy advisor to Jesse Jackson (this is apparently how Jackson got involved with the PLO--more info in Kenneth Timmerman's Shakedown) and associated with Mary Francis Berry at Pacifica Radio in the 1990s. There's an FR thread with detailed info here:

MARTIN LUTHER KING JR. - Congressional Record - CPUSA

King himself was not a CP member, according to former FBI official Cartha DeLoach, but it was his association with Levison and O'Dell that led the Kennedy administration (not just LBJ, contra Matthews) to place him under surveillance.

[AmeriBrit]

Thanks for the great link Fedora, a definite keeper.