New York Times reporter Philip Shenon's A Cruel and Shocking Act reaches a similar conclusion. Despite the obligatory come-hither subtitle The Secret History of the Kennedy Assassination it's a judicious account of the Warren Commission, as recalled by the lawyers who did its legwork. Shenon too believes Oswald did it, but claims that ''senior officials at both the CIA and the FBI hid information from the panel,'' apparently hoping to conceal what they'd known about him, and ''important witnesses...were ignored or threatened into silence.''
Shenon's prime Person of Interest is Sylvia Duran, who worked in the Cuban consulate in Mexico City, where Oswald seems to have visited in September 1963. Did she, as has been alleged, take him to a party attended by Cuban diplomats and spies and, tantalizingly, an unnamed American movie star where guests did the twist and wished for Kennedy's assassination? She denied it when Shenon tracked her down, but relatives and friends confirm the story. If true, of course, this still wouldn't prove anything except loose talk and looser investigation. Kennedy's successor, Lyndon Johnson, privately believed Castro was behind the assassination, but Shenon blames only official secrecy for ''the conspiracy theories that are likely to plague us forever'' and for you guessed it ''a swirl of unanswered questions.'' CIA paper-handlers covering their asses don't have the pop appeal of grassy-knoll gunmen, but 50 years into the Kennedy case, readers still in search of a shudder will have to settle for what they can get. A