AMERICANS have always had a penchant for conspiracy theories - from arguments that the assassination of Abraham Lincoln might have been linked to hostile Cabinet members, to suggestions that Franklin D. Roosevelt secretly allowed the bombing of Pearl Harbor. But no United States historical occurrence in recent memory has produced as many explanations as the terrible events of Nov. 22, 1963, when John F. Kennedy was gunned down in a crime that altered the course of the US political landscape and helped shatter America's sense of postwar invincibility.
Now, 30 years later, Gerald Posner, a former Wall Street lawyer who has written several investigative books, has produced the most authoritative work to date on the Kennedy assassination. Posner wants to scrap assassination theories involving Soviet agents, Mafia hit men, rogue CIA officers, right-wing militarists and pro- and anti-Castro Cubans all plotting together to bring down the youthful president - all of which were woven together in Oliver Stone's riveting 1991 film ``JFK.'' Posner's conclusion ends where the Warren Commission report began - with the assumption that the assassin, a lone gunman, was Lee Harvey Oswald.
Using his analytical legal skills and an investigative reporter's bent for detail, Posner has re-indexed all 26 volumes of the Warren Commission testimony and the report of the House Select Committee on Assassinations, interviewed more than 200 people, including Yuriy Nosenko, a top Soviet KGB official, and used extensive computerized electronic-monitoring techniques to reconstruct the course of the bullets fired at the president - particularly the third, believed to have been the fatal one.
Conspiracy buffs will spare no effort to take Posner's conclusions apart. But his gripping and convincing depiction seems likely to stand as the starting point for any future examination of Kennedy's death.
Posner's finest accomplishment may well be his focus on Oswald. His Oswald is a remorseless, humorless individual who as a child enjoyed throwing rocks at other children, who as an adult was physically abusive toward his wife, Marina, and who once attempted to assassinate retired US army Major General Edwin Walker in Dallas, using the same Italian-made World War II Mannlicher-Carcano rifle that was carried to the sixth floor of the Texas School Book Depository and aimed at the president.
Posner's most controversial argument, however, is his technical discussion of the shooting, using computerized graphics of bullet trajectories. In Chapter 14, along with Appendix A of his book, Posner shows how it was possible for Oswald to squeeze off three shots in eight seconds - enough time to kill the president. Posner bases his judgment on a frame-by-frame electronic analysis of the famous 8-millimeter film of the assassination taken by Abraham Zapruder, a private citizen who went to Dealey Plaza with a movie camera in hand (the film is shown in ``JFK'').
Posner concludes that Oswald fired three shots and there was no fourth shot, as some bystanders have alleged and which would have required a second gunman. The second bullet, he concludes, hit both President Kennedy and Texas Governor John Connally.
Despite all the praise being lavished on this book, one suspects that the file on Dallas is far from closed. Nor should it be. Computerized enhancements of bullet trajectories aside, the troubling question still involves motivation. Posner attributes the crime to Oswald's troubled past and malevolence; but that explanation is almost as tidy as many of the conspiracy theories.