When he first caught a glimpse of the papers in an Atlanta document dealer's office in December 1994, "my tongue was out to my knees," recalls reporter Seymour Hersh. And why not? It looked like one of the juiciest discoveries yet in the epic journalistic deconstruction of the Kennedy presidency. The documents purported to show that Kennedy had set up a trust fund of $600,000 for Marilyn Monroe's mother, supposedly to buy the actress's silence over her alleged affair with the President.
That startling revelation was on track to make headlines--MARILYN BLACKMAILED J.F.K.!--for the book that Hersh had spent more than...