JFK Assassination Conspiracy Theory Debunked by New Gunshot Study

On November 22, 1963, U.S. President John F. Kennedy was assassinated by a sniper while riding in an open motorcade through downtown Dallas, Texas, in a moment that shook the world.

Despite official investigations concluding that Lee Harvey Oswald was the lone assassin—firing three shots from the window of a nearby building—conspiracy theories abound to this day, fueled by apparent irregularities in the findings.

One long-held and famous conspiracy theory holds that JFK was shot by a second gunman from a grassy knoll. While the flaws of this theory have already been pointed out by some, a new study published in the journal Heliyon may finally put the idea to rest.

Supporters of this theory tend to use the infamous Zapruder film—which captured the killing—to bolster their claim, pointing to the fact that Kennedy's head moves in a backward and leftward motion after the bullet's impact, apparent proof that he was shot from the front as well as from behind (by Oswald).

But new analysis of the Zapruder footage conducted by Nicholas Nalli from I.M. Systems Group shows that JFK’s reactions after being shot are physically consistent with the results of the official autopsy findings: that he was killed by a gunshot to the back of the head, fired from a high-energy Carcano rifle (the one used by Oswald) located in the vicinity of the Texas School Book Depository.

For his study, Nalli was particularly interested in one crucial part of the film, in which the president's head can be seen momentarily snapping forward at the moment that the fatal bullet made impact—just before it moves backward and to the left. While Nalli is not the first person to notice this detail, his analysis, which is based on classical physics, is the first to analyze it so thoroughly and quantitatively.

"Rather than gloss over this fact, as has been done by most previous authors, including anti-conspiracy authors, I chose to study and model it explicitly," Nalli said in a statement. Kennedy's head moving back and to the left, Nalli claims in the statement, was due to a recoil effect.

GettyImages-76312243 John F. Kennedy, then U.S. president, is struck by an assassin’s bullet as he travels through Dallas in a motorcade, on November, 22, 1963. In the car next to him is his wife, Jacqueline, and in the front seat is John Connally, then Texas governor. The “second gunman” theory has recently been debunked by a new gunshot study. Three Lions/Hulton Archive/Getty Images

To make his findings, Nalli created a gunshot wound dynamics model to explain the forward head snap using known parameters from the crime scene, including the mass, speed and diameter of the bullet, the shutter frequency of the camera used to make the Zapruder film and data from the autopsy.

The new findings do not necessarily rule out a broader conspiracy, but they do pour water on the theory that the fatal shot was fired from the grassy knoll.

"I found that the Zapruder film shows President Kennedy being shot from behind and not from the infamous grassy knoll, in corroboration of the official autopsy findings—that's the only 'smoking gun' in the film," Nalli said.

Join the Discussion