Newswise — There are many conspiracy theories about who assassinated President John F. Kennedy. So many, in fact, the suspect assassinators would have to be standing shoulder to shoulder on the grassy knoll or perched on each other's shoulders in the Texas School Book Depository. According to a 2001 Gallup poll, 81 percent of Americans believe the assassination was a conspiracy, while only 13 percent subscribe to the Warren Commission's "lone nut" theory.

"It's preposterous on the face of it to believe that a mousy little guy with a $12.95 rifle could bring down the leader of the free world," says Kenneth Rahn, a professor emeritus at the University of Rhode Island. "Yet," says Rahn, "that's exactly what Lee Harvey Oswald did 41 years ago this November 22."

Relying on science, in particular neutron activation analyses and ballistic evidence, instead of speculation, Rahn, a retired oceanographer and atmospheric chemist, and Larry Sturdivan, a retired wound ballistics specialist at the Army's Aberdeen Proving Ground in Maryland, argue that the president and Texas Governor John Connally were hit by two and only two bullets, both fired from Lee Harvey Oswald's rifle. They base their results on a review of ballistic and chemical analysis of the recovered bullet fragments. Furthermore, they prove statistically that the odds of additional successful gunmen are 2 to 3 percent at best and one in a million at worst. Results of their research were published in this month's issue of the Journal of Radioanalytical and Nuclear Chemistry.

According to the Warren Report, three shots were fired on that fateful day in November. Since Oswald's bolt-action rifle required 2.3 seconds per shot and the shots were fired within 4.8 seconds, conspiracy theorists, assuming that Kennedy was hit by the first shot, claim that it would have been difficult, if not impossible, for Oswald to act alone.

Rahn and Sturdivan show that a three-hit scenario is ruled out by the neutron activation data. They further argue that Oswald's first shot most likely missed the president's car completely. This provides at least 4.8 seconds between the two shots that hit, making it an easy feat.

Oswald's second shot hit the president in the neck/upper back area, exited through the throat, and continued through Connally's body, exiting out of the governor's thigh. The third and fatal shot hit the president in the back of the head. "The sequence is the bullet entered, exited, and its energy created an explosion in the president's head, creating massive damage. Fragments from the bullet cracked the windshield," says Rahn, a founding member of Nonconspiracists United, a newly formed group with its own e-mail discussion list. He has recently established a website, .

Five bullet fragments, two large ones, and three small ones were recovered from the limousine, Connally's stretcher in Parkland Hospital and from the men's bodies. The fragments were examined twice by neutron activation analyses, first by the FBI in 1964 and then by Vincent Guinn, a professor of chemistry at the University of California at Irvine in 1977.

The first large bullet fragment, found on the stretcher, had a deformed, but complete shell with jacket markings on the jacket. It was a perfect match to Oswald's rifle. The second large fragment, which had bounced onto the front seat contained lead, and some jacketing with some markings and brain tissue. It, too, was a perfect match to Oswald's rifle.

The three smaller fragments had no jackets and so couldn't be matched ballistically, but they could be matched chemically since this particular ammunition had unusual chemical properties. The ammunition manufacturer had combined scrap lead containing antimony, a hardening additive with virgin lead, but had not mixed the vats completely.

Both the FBI and Guinn appeared to group the fragments into a body shot and head shot. However, the FBI set contained a systematic error and Guinn's results had potential problems. The core of the fragments was heterogeneous so that critics charge that different results could be obtained. Guinn overcame the FBI's systematic error, and Rahn and Sturdivan overcame the heterogeneity problem by showing that it was a non-issue. The heterogeneity actually proved to be critical to grouping the fragments into the remains of the two and only two bullets.

The benefits of nuclear activation analyses extend beyond limiting the hits to two bullets, by providing the only way to prove that Oswald's rifle was fired that day, and thereby quash the rumors that it had been planted to frame Oswald. They also render the details of the headshot and back wound irrelevant. They lead to the best-documented shooting scenario to date, namely an early miss, a single bullet through both men's bodies, and the killing hit to JFK's head five seconds later. Most importantly, nuclear activation analyses ties much of the physical evidence together and brings Oswald much closer to the crime by proving that his rifle did it all.

So the mob, Castro, the CIA, the Russians, Vice President Lyndon Johnson or the countless other supposed conspirators aren't the bad guys. Although society seems to need to feel that only great plots can take down great men, the two scientists argue that Oswald, alone, took his shot at history. A shot that forever changed the course of our nation and gave birth to America's skepticism.

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Journal of Radioanalytical and Nuclear Chemistry (Nov-2004)