There have been two government investigations. Hundreds of witnesses saw it happen. And the whole thing was captured on film. But 50 years later, many Americans still have doubts about what really happened the day President John F. Kennedy was shot. 

And thanks to the Internet, we're not getting any closer to a consensus.

Conspiracy theories implicating everyone from the Soviets to the CIA to the Mafia existed well before the Internet came into being, but experts say the Web has fundamentally changed the way these theories develop and spread throughout society. 

"It's a more social experience than it used to be," said Mark Fenster, a professor at the University of Florida Law School and the author of Conspiracy Theories: Secrecy and Power in American Culture.

"Two decades ago, you occasionally had groups of conspiracy theorists physically getting together for meetings and conventions," Fenster added. "Now the conversation is constantly happening online."

The Internet isn't really bringing new converts into the world of JFK conspiracy theories, he told the Daily Dot, but it is intensifying the experience for those who already reject the government's official conclusion that Lee Harvey Oswald acted alone that late November day in 1963. It's also making it easier for new conspiracy movements, like the 9/11 Truthers and Obama Birthers, to gain traction.

It didn't take long after Kennedy's death for skeptics to start raising doubts about the official conclusions offered by the Warren Commission. According to Gallup, in the days immediately following the assassination, 52 percent of Americans already believed there was more than one person involved in the shooting. That number would rise as high as 81 percent by 1976. Today, 63 percent of the country still believes there was a conspiracy.

The Kennedy assassination has continually attracted controversy due to several key ambiguities about the shooting. The type of gun Oswald use would have limited the number of shots at the president's motorcade to three, but many insist that eyewitness accounts and the bodily injuries caused are evidence of at least a fourth bullet and a second shooter. There's also the infamous "back and to the left” motion of Kennedy's body when he was fatally shot in the head, as captured by Abraham Zapruder in his famous filn of the event. A number of conspiracy theorists see this as clear evidence the lethal bullet came from a nearby grassy knoll instead of the book depository window Oswald used as his sniper's perch.