Doubt cast on JFK 'lone assassin' theory

More than 40 years after he was fatally shot in Dallas, researchers have added fresh fuel to the speculation over who was involved in the assassination of President John F Kennedy by claiming the original bullet analysis was flawed and cannot rule out that a second gunman was involved.

Using new scientific techniques not available to previous researchers and analysing bullets from the same batch purportedly used by Lee Harvey Oswald, the team has argued that it cannot be assumed that Oswald was the only assassin involved. While they do not claim evidence to prove a second gunman participated, they say the original fragments of the bullets recovered from the scene of the shooting should be re-examined.

"Given the significance and impact of the JFK assassination, it is scientifically desirable for the evidentiary fragments to be reanalysed," the researchers write in the journal Annals of Applied Statistics.

Kennedy, the 35th US president, was fatally shot as his motorcade passed through Dealey Plaza in Dallas on 22 November 1963. The official Warren commission that investigated the killing concluded the following year that the president had been killed by two of three shots fired by Oswald - his first shot having missed - from the 6th floor of the Texas School Book Depository.

The second shot - the so-called magic bullet - struck Kennedy in the back and exited through his neck before striking the Texas Governor John Connally, who was travelling in the same limousine. The third shot hit Kennedy in the head and killed him.

Despite the official conclusion that Oswald acted alone, there has been endless speculation other gunmen participated in the killing and that the authorities sought to cover up their participation. Grainy photographs and footage from a home movie, the Zapruder film, are examined for other possible assassins standing on the grassy knoll or else behind the white picket fence - locations surrounding Dealey Plaza that have entered conspiratorial lore.

The team arguing that five fragments of bullet recovered from Dealey Plaza be re-examined include William Tobin, the FBI's former chief metallurgy analyst, who examined evidence from cases such as the 1995 Oklahoma City bombing and the 1996 bombing of TWA Flight 800.

The Washington Post reported yesterday that after he retired, Mr Tobin drew national attention by questioning the FBI's methods of matching bullets to suspects based on their lead content. As a result of his questions, the bureau switched its methods.

The original analysis, based on lead content, concluded the five fragments came from just two bullets, traced to the same batch that Oswald bought. Mr Tobin and his colleagues purchased bullets from the same batch owned by Oswald - available on the internet as collectors' items - and used new techniques to analyse them. They found the science and statistical assumptions used by the original examination to conclude the fragments were from just two bullets was wrong.

"This finding means that the bullet fragments from the assassination that match could have come from three or more separate bullets," the researchers write. "If the assassination fragments are derived from three or more separate bullets than a second assassin is likely."

Conspiracists have received support from many areas, not least Oswald's background as a visitor to the Soviet Union and his interest in Cuba. The fact that he himself was shot just days after the assassination by a man with low-level links to the Mafia - and who himself died soon afterwards from cancer - have only added to speculation.

A 1979 report by the House Select Committee on Assassinations concluded it was likely Oswald acted as part of a conspiracy and that a second gunman is likely to have fired at Kennedy but missed.

But for each point raised by the conspiracists, others have been able to offer a rebuttal. Just last month, former prosecutor Vincent Bugliosi published an exhaustive 2,792-page book, Reclaiming History, that also concludes Oswald acted alone and seeks to knock down most, if not all, the surviving conspiracies.

Despite this, polls show that a majority of Americans still believe there was more to Kennedy's assassination and the official version is not complete. Gerald Posner, author of Case Closed, another convincing study that concludes Oswald acted alone, hits upon one reason why people cannot accept that Oswald, armed with a $12 rifle, could be responsible for such an epic event.

In the book he quotes the historian William Manchester: "Those who desperately want to believe that President Kennedy was the victim of a conspiracy have my sympathy. If you put the murdered President of the United States on one side of the scale and that wretched waif Oswald on the other side, it does not balance. You want to add something weightier to Oswald."

The conspiracy theories

* Kennedy was killed by Cuban agents in retaliation for the Bay of Pigs invasion of 1961.

* Four gunmen killed Kennedy but Oswald was not among them and knew nothing of the plot - a theory expounded by Ron Rice, a member of staff at Dallas's Conspiracy Museum.

* Vice-President Lyndon Johnson, who then became President, arranged the assassination - a theory outlined in a book by Barr McClellan, father of President Bush's former spokesman Scott McClellan.

* A second gunman was involved in the killing, a theory given even more oxygen by Oliver Stone's 1991 movie JFK which shows a puff of gunsmoke on the plaza's grassy knoll. Norman Mailer has also posited this theory.

* Kennedy's killing was organised by the Mafia because of the increasing pressure put on them by his brother, the attorney general, Robert Kennedy.

* Israel organised the killing to retaliate against Kennedy's opposition to its nuclear weapons ambitions.