'61 C.I.A. Poison Plot Reported Against 3 Top Leaders in Cuba
Source says CIA organized attempt in early '61 to poison Cuban Premier F Castro, his bro Raul, and Ernesto Che Guevara because CIA believed they would be capable of rallying Cuba after a counterrevolutionary invasion then being planned; says assassination plot was directed by alleged organized crime figures Sam Giancana and John Roselli; says planning began during Eisenhower Adm in latter 1/2 of '60; says CIA project officer in case was Sheffield Edwards; says Edwards recently told Sen Select Intelligence Com that he enlisted Robert A Maheu to serve as CIA's liaison with criminal underworld figures to arrange the murders (M)