Nearly all Americans above a certain age can recall where they were the moment they learned of the assassination of John F. Kennedy. A much smaller number can recall where they were when they discovered who really did it.

One of these few was sitting in a dripping raincoat in a reading room on the fifth floor of the Lauinger Memorial Library at Georgetown University, in Washington D.C., on a rainy April day in the year 1977. On the wooden table before him was the sort of hinged cardboard box, the size and shape of a large book, that attorneys use to keep together all the material connected with some legal combat: a literal "case." Within it were several dozen typed pages, including a letter from a United States senator, several memoranda from the files of the Central Intelligence Agency and the Federal Bureau of Investigation, a thick packet of handwritten notes on lined yellow paper, two bankbooks, a small ledger, some photographs and clippings, a tape cassette, and a reel of 8-mm home movie film. There was also a sealed olive jar full of alcohol in which floated a chunk of human flesh.

The man shivered and stood to remove his sopping raincoat. A young woman, four seats down at the long table, glanced up at him from her thesis research (American Policy in Honduras, 1922-39) and then, a moment later, gave him a longer look, for the reading she was doing was tedious and he was not an ordinary-looking man.

He was very tall, for one thing, a bit over six-feet-five. His body, in its damp and rumpled dark suit, was broad-shouldered and rangy. He walked over to a display case and seemed to stare unseeing at a selection of colonial maps, and she could see that he walked with a slight limp.

His face, profiled, was moderately beaked and high cheekboned, the eyes having a slight oriental cast, and the sallow skin of his face and the lank dark hair, soaked and plastered tight against his skull, contributed to the general impression of the East-some Tatar or gypsy blood perhaps, she thought. You got to see all kinds in the Georgetown library.