Fifty years ago, John F. Kennedy was shot in Dallas and Lee Harvey Oswald was arrested for the crime. Depending on whom you ask, however, that may be either all we really know about the assassination or all there is to know. No crime in American history has inspired as much debate—or as many books—as the events of November 22nd, 1963. Not all conspiracies are created equal; we asked twelve scholars of the crime of the century for the most unbelievable theories they’ve ever heard.

Vincent Bugliosi, author of Reclaiming History: The Assassination of President John F. Kennedy

The secret service agent whose gun accidentally goes off and kills the president. Its just unbelievable. In the first place, no one heard his gun go off. There were nine other people in that limousine, and they didn’t hear a gun go off. You normally would, if you’re sitting one or two feet from someone and their gun goes off. The notion that he fell backward, and the gun went off and just happened to hit the president in the same place Oswald had been aiming at, but had happened to miss a second earlier. To show you how not credible these sorts of theories are, at one time or another, conspiracy theorists have accused 42 groups, 82 assassins, and 214 people by name of being involved in the assassination.

Priscilla Johnson McMillan, author of Marina and Lee: The Tormented Love and Fatal Obsession Behind Lee Harvey Oswald's Assassination of John F. Kennedy,

The most outrageous theory about the assassination would be any theory that says Lyndon Johnson had anything to do with it. This is a popular theory because one of maddening things about the Kennedy Assassination, what people cannot accept, is the disparity between the magnitude of the deed and the insignificance of the perpetrator.

Anthony Summers, author of Not in Your Lifetime: The Defining Book on the J.F.K. Assassination

One is spoiled for choice. The notion that a member of the President's Secret Service detail shot JFK by mistake rates high amongst theories that some take seriously. Then there is the proposal that an impostor lies buried in Oswald's grave. Ludicrous, yet it led to the body being exhumed. At the crazy extreme, I keep an initially sane-sounding letter that offered to prove Kennedy was merely "removed from office" and escaped by crouching down on the floor of the limousine. This rates high in my Loonies file. There is a very basic reason that almost 60% of the American people think there was a conspiracy. They are confronted by a great contradiction. The first official investigation, the Warren Commission, found that there was a lone gunman, Oswald, while the House Assassinations Committee concluded that there was "probably" a conspiracy. That aside, people have now had well over forty years of hearing conspiracy theories ranging from the credible to the deranged. Finally, for many people - and this is society's problem - the mysteries of the assassination have become grisly entertainment. To a great extent, blame the media for that.

Dean R. Owen, author of November 22, 1963: Reflections on the Life, Assassination, and Legacy of John F. Kennedy

The most outrageous conspiracy theories are that there was a “double” to Mr. Oswald and that the Warren Commission combined the biographies of two men into one, that Mr. Oswald was a CIA operative who had become a security risk, Mr. Oswald had been paid by a representative of Cuban leader Fidel Castro to assassinate the president. The culture of assassination conspiracies is fueled, in part, by the improbability that Lee Harvey Oswald, an odd, some might say disturbing, individual, could have acted alone. How is it that our 35th president was gunned down by a lone Communist armed with a $12 rifle and delusions of grandeur, in a city that, as Robert F. Kennedy Jr. characterizes in my book, was “a seething cauldron of right-wing depravity?” The only person able to explain fully his reasons was himself killed two days later.

Mark Fenster, author of Conspiracy Theories: Secrecy and Power in American Culture

I would put the entire genre of alien conspiracy theories in there. Most of them are focused on Kennedy's supposed knowledge of or interest in aliens and alien abduction. No doubt someone has alleged the reptilians did it. I prefer plausibility in my conspiracy narratives. At a certain level, many of them are plausible. There are enough anomalies and coincidences in the event and enough mysteries surrounding it, and that period in political history is so rich, that many of the earthly theories seem at least minimally believable. My preference for consuming CIA-based conspiracies is personal and not particularly rational, given that I'm not convinced that the CIA of that era has shown itself as an organization to be exceptionally competent at doing anything but ruining other countries and people's lives in openly secretive ways. Pulling off a JFK hit and keeping it secret this long would be the mark of an incredibly competent plot.

James Piereson, author of Camelot and the Cultural Revolution: How the Assassination of John F. Kennedy Shattered American Liberalism

I think the most outlandish is David Lifton’s theory—from his book Best Evidence: Disguise and Deception in the Assassination of John F. Kennedy—that Kennedy’s body was stolen between Dallas and Washington, and his wounds were altered to suggest he was shot from the back when in fact he was shot from the grassy knoll. That seems to be the wackiest I’ve encountered. Then there’s the one involving Francis Gary Powers, who was shot down in a U-S flight over the Soviet Union in the spring of 1960—when the U.S, was sending surveillance flights over the Soviet Union. Oswald served at an Air Force Base in Japan from 1958 to 1959 where flights like these were taking off. He was a radio operator there. He wasn’t given access to the U-2, but the enlisted men saw these planes taking off from the base. Powers, after he was shot down, was exchanged for a Soviet spy in 1962. He came back and wrote a book in which he claimed that Oswald gave the Soviet union the information they needed to shoot down the U-2—how high they fly, where to aim their surface to air missiles. That has never been authenticated and the CIA has always denied it. What are the chances this one man, Lee Harvey Oswald, was involved in the two most major incidents of the Cold War?

Jefferson Morley, former Washington Post reporter and author of Our Man in Mexico; Winston Scott and the Hidden History of the CIA, and founder of jfkfacts.org

One of the more ludicrous JFK theories is that the Federal Reserve was somehow involved in the death of JFK. There is no zero evidence to support this claim often made by foes of the Fed. The biggest problem is not that such unfounded theories are ludicrous but that they are pernicious. They served to confuse people and distract the public from the real news in 2013 that the CIA retains 1,100 secret files related to JFK's death that it will not release until 2017 at the earliest.

John McAdams, author of JFK Assassination Logic: How to Think about Claims of Conspiracy

People don’t want to believe very small causes have very large effects. People like to see more order in the universe. Lee Oswald’s mother, Margerurite, said it was a mercy killing. She learned that Kennedy had Addision’s disease, and said that Kennedy was going to slowly decline and it was better to get rid of him immediately then have him fall into ill health. For a while there was a website that said the masons killed Kennedy, and that they were reenacting in Dealey Plaza a Masonic ritual called the Assassination of King Hammurabi. Which is utterly absurd. For a while there was the idea surrounding the “umbrella man” in Dealey plaza, who has an umbrella open--Robert Culter said there was a dart gun hidden in that, and the Umbrella Man fired the dart gun, hitting Kennedy in the throat to paralyze him so he could be shot in the head. Why not just shoot him in the head? And then there’s the driver did it. If you look at a really bad copy of the Zapruder film, it will look like William Greer, the driver, reached over his shoulder with a gun and shot Kennedy in the head. But his hands were on the steering wheel the whole time, it only looks differently in a very bad copy of the Zapruder film. There was a guy called Bill Cooper who would travel around showing people this, and he convinced a lot of people!

Larry Sabato, author of The Kennedy Half-Century: The Presidency, Assassination, and Lasting Legacy of John F. Kennedy

There are a couple of new books out that say Lyndon Johnson did it! Lyndon Johnson did not do it. There’s no hard evidence of that, its ridiculous. Then there’s another book saying Oswald was shooting at governor John Connally, not Kennedy. Oh, please! Its amazing what people will buy! The more outrageous your theory, the better your book sells. But the most outrageous is the idea that the secret service killed Kennedy. They were trying to fire at the presumed assassin or assassins and accidentally fired the headshot. Utterly absurd!

Jim DiEugenio, author of Reclaiming Parkland: Tom Hanks, Vincent Bugliosi, and the JFK Assassination in the New Hollywood

Besides Oswald did it? Its pretty hard to top that one, that Oswald did it. Its pretty hard to top that one with all the evidence we have today. Oswald was not on the sixth floor, he never ordered that particular rifle that was found and put into evidence, he ordered a slightly different one. The shells found on the sixth floor were not arranged how they’re shown in the Warren Commission, they were rearranged. There was no sniper nest, that was another thing that was reconstructed later. Take a look at that evidence, its hard to believe. There are some really wild theories, that it wasn’t Kennedy’s body, but police officer J.D. Tippit’s that wound up in the autopsy at Bethesda, crazy fringe things like that.

Lamar Waldron, author of The Hidden History of the JFK Assassination

Old theories that were discredited before the internet have now been revived. The theory that a secret service agent shot JFK. You know, there were a lot of people at Dealey Plaza, and a lot of people shooting films, and they don’t show that. the guy who wrote that book had to write a letter of apology because he was sued by that secret service agent. But now that people are looking at the assassination on YouTube, that’s come around again. There’s a theory that says JFK was shot by the driver! That was being promoted by a UFO crackpot in the eighties. You can clearly see the driver did not do it, but sure enough, you can go to YouTube right now, search “Driver shot JFK” and you’ll find videos that claim to show that. Just as ridiculous is the idea that Castro killed Kennedy! That Castro would want Lyndon Johnson to be president, Lyndon Johnson was no great friend of Cuba. If anything he was much more conservative than JFK, why would Castro risk the annihilation of his country to make him president?

Lance deHaven-Smith, author of Conspiracy Theory in America

The most outrageous theory of the assassination is the account presented in the Warren Commission report. President Kennedy had bullet wounds in his back, neck and head. Governor Connally had wounds in his back, chest, arm, and leg. A single bullet is said to have caused all these wounds except the wound to the president’s head. This is ludicrous on its face. Furthermore, this single bullet is said to have entered the president’s back almost six inches below the collar of his shirt and to have exited the front less than an inch below the collar button, meaning that the trajectory of the bullet, if there was in fact just one bullet, was upward from the president’s back to his front. Clearly, a bullet fired from 6 floors up and behind the president would have had a downward trajectory. Add to this the evidence from the Zapruder film that when the President was shot in the head, his head flew back, indicating a shot from the front. The assassination of President Kennedy attracts theories of conspiracy because the most basic evidence in the record—the bullet wounds on the bodies of the two victims—points directly to multiple shooters. There are of course many other problems with the Warren Commission theory, but what makes it so ridiculous is that it is directly contradicted by the evidence presented in the Warren Commission report itself.