JOHN F. KENNEDY has been the subject of so many investigations, reminiscences, probes, ruminations, theories, and examinations that today, 30 years after his assassination, the Library of Congress contains twice as many books about him as it does about Elvis.
There are the classics, such books as ``Death of a President'' by William Manchester, and Arthur Schlesinger's ``A Thousand Days.'' There are self-published assassination volumes: ``Is President John F. Kennedy Alive - and Well?,'' by Bernard Bane, is in its 14th printing. There are entire books on the grassy knoll, the magic bullet, and JFK's scrimshaw collection.
At the heart of this enduring fascination with President Kennedy's life and death is their mystery.
There is the mystery of his murder, of course, but there is also a mystery of the living foregone, of what he would or wouldn't have accomplished, of what kind of man age would have revealed him to be.
On the anniversary of JFK's death, debate about his legacy seems, if anything, more heated than ever.
``He was a complicated, interesting individual who has been seen through many different prisms,'' says Fred Greenstein, a presidential scholar at Princeton University.
His first prism-image was one of vitality. At the time of his election, he seemed an antidote to his stodgy predecessor, Dwight Eisenhower.
Kennedy played touch football instead of golf, had all his hair, favored political movement over inaction. Since the 1960s, historians have begun to see Ike as a shrewder chief executive than his public persona - but at the time, it was JFK who seemed to stand for the future.
His second prism-image was one of martyr. After Lee Harvey Oswald (or some other assassin, if one believes conspiracy theories) pulled the trigger in Dallas, any doubts about his administration were subsumed in collective grief over the lost promise of Camelot.
In late 1963, many in Washington thought Kennedy's presidency to that point had involved more flash than substance. Hard work on domestic issues such as civil rights and medical care for the elderly was left for Lyndon Baines Johnson. Yet it was Kennedy who brought these problems to the nation's attention, argues one historian. Ironically, his death may have made it easier for them to be addressed. LBJ benefited from his predecessor's political spadework.
``Federal aid to education, passage of Medicaid ... Kennedy put those things on the political agenda,'' says Ed Berkowitz, a professor of political science at George Washington University.
In the decades since his death, Kennedy's prism-images have continued to proliferate. They are no longer artificially idealized. Alleged affairs with many women - including one, Judith Exner, who had Mafia ties - have greatly tarnished his image as head of a happy family. Public polls still consistently rank Kennedy as the most popular modern president. But, perhaps inevitably, professional historians now find his legacy mixed.
Kennedy's domestic advances were largely technocratic, such as his tax cut. And his foreign affairs record no longer looks as tough-minded as it once did. If anything, new documents indicate that his decision-making during the Cuban Missile Crisis may have inadvertently ratcheted up tensions with the Soviets.
``In retrospect, one thing to be said about the Kennedy presidency is it had an endlessly disorganized and not-thought-through foreign policy process,'' says Dr. Greenstein.
In the final analysis, however, the burning question about JFK does not involve who he was, and what he did. It is, ``Who killed him?''
The Warren Commission explanation, that a loser named Lee Harvey Oswald carried off the historic deed himself, and then was conveniently shot by another loser named Jack Ruby, seems preposterous. History is full of preposterous truth - but no matter. A new CBS poll finds half of Americans believe the Central Intelligence Agency had something to do with Kennedy's death.
The Library of Congress computer lists 506 books in its general JFK file. Of those, fully 250 deal with his assassination. Many purport to contain the one true story. Titles are full of assertions: ``The Biggest Lie Ever Told''; ``Destiny Betrayed''; ``How Kennedy Was Killed: The Full Appalling Story.''
For all their minute analyses of such items as the path of the infamous, tumbling magic bullet, the heart of these conspiracy theories is that the job was just too big for Oswald alone.
The Mafia/CIA/Castro/Communists/Arms Dealers had to be involved, theorists say.
Oliver Stone's movie ``JFK'' has given a tremendous boost to the Kennedy conspiracy industry. Partly because of Mr. Stone's goading, Congress last year passed a bill mandating timely release of all government files relevant to JFK's killing.
Not that full release will quiet skeptics. ``People aren't going to find a smoking gun proving the CIA did it. And those who think there's a conspiracy will say - `well, they destroyed those documents,' '' says Robin Marra, a Southern Methodist University political scientist.