More than 50 years after President Kennedy was assassinated, the majority of Americans apparently believe in a conspiracy theory about his death. In fact, FiveThirtyEight reports that 61 percent of people think Kennedy's death involved multiple players. But this week could bring some closure to those theories. On Friday, approximately 3,600 previously classified documents pertaining to Kennedy's murder will be made public for the first time, and the information held in these files could debunk even the most absurd of rumors. Unfortunately, the trove of interviews and other documents probably won't be so revelatory. “Most of the information due to be disclosed at the end was classified as ‘not believed relevant’ to the assassination when the Review Board initially met in the 1990s,” according to Time.That said, historians will most certainly still pore over these papers, seeking any clue that could help decipher one of the most infamous crimes of the century. In the meantime, here are the most enduring conspiracy theories about JFK's assassination:The Grassy KnollIn 1964, the Warren Commission concluded that Lee Harvey Oswald acted alone (and that Jack Ruby also acted alone when he killed Oswald two days later), but most people don't seem to accept that this assassination was the work of a lone gunman. The House of Representatives may be partially to blame for this enduring conspiracy theory. In 1976, the Select Committee on Assassinations, which reinvestigated JFK's killing as well as Martin Luther King Jr.'s, concluded that there was "probably" a second shooter on the "grassy knoll," a hill overlooking the site where Kennedy was assassinated in his motorcade.In 1982, yet another committee examined the evidence. The National Academy of Sciences Committee on Ballistic Acoustics found that "reliable acoustic data do not support a conclusion that there was a second gunman."But the theory lives on.The Umbrella ManWhy would someone carry an umbrella on a sunny day? Clearly people who believe the umbrella man conspiracy never get sunburned. Louie Steven Witt carried a black umbrella with him to Dealey Plaza on November 22, 1963, and was caught in the famed Zapruder film raising it into the air as Kennedy's car drove past. Some have claimed he was giving a signal; others think he could have shot a poison dart from the umbrella. But the truth is much less exciting. During a 1978 interview with Witt, he revealed that he simply wanted to heckle the president. Apparently, Witt, a "conservative type fellow" had heard the umbrella was a "sore spot" with the Kennedy family, due to its association with British Prime Minister Neville Chamberlain, who, like JFK's father Joseph Kennedy supported appeasement prior to World War II.It was a mob hit.The Kennedys were no strangers to organized crime. In fact, some believe the mafia helped JFK steal the election in 1960 by securing votes in the key state of Illinois. However, another conspiracy theory has the political dynasty at odds with the mob.This theory hinges on the fact that Kennedy was unsuccessful in overthrowing Fidel Castro in Cuba, meaning the mafia-run casinos remained shutdown, and that his brother, Robert Kennedy, was cracking down on the mob in his role as attorney general, pursuing a case against Jimmy Hoffa.“Robert Kennedy had a fear that he had somehow gotten his own brother killed,” according to biographer Evan Thomas. “That Robert Kennedy’s attempts to prosecute the mob and to kill Castro had backfired in some terrible way, had blown back, as the intelligence folks say...Bobby thought that he'd be killed, not his brother and now he has this daunting, horrible realization, or fear that all of his attempts to get the mob and to get Castro have in some terrible way blown up and come back to haunt his family and, and resulted in, in the death of the president, his brother."The government did it.Perhaps the most frightening theory in circulation is that the Kennedy assassination was an inside job. According to biographer Philip Shenon, that was Bobby's first thought. "Apparently Bobby Kennedy’s first suspicion was that it was some rogue element in the CIA," Philip Shenon told NBC News. However, after a meeting with CIA Director John McCone, Kennedy changed his mind. The public was harder to sway. Of course, an organization that's shrouded in secrecy and has a motive (CIA leader's were notably angry with Kennedy over the Bay of Pigs Invasion), is always going to be suspect, but the organization maintains it had nothing to do with the crime."While the CIA conspiracy theories make good fodder for movies, they are pure fiction," CIA spokesman Edward Price told NBC.Other insider assassination theories have included a story that William Greer, the driver of the President's car, turned around and shot JFK, a premise based on a poor copy of the Zapruder film.Ted Cruz's father was somehow involved.This is a relatively new one. During the 2016 presidential election, then-candidate Trump implied that his fellow Republican candidate Ted Cruz's father was a known associate of Lee Harvey Oswald. "His father was with Lee Harvey Oswald prior to Oswald being, you know, shot," Trump said on Fox News during a phone interview. "I mean the whole thing is ridiculous. What is this? Right? Prior to his being shot. And nobody even brings it up. I mean, they don’t even talk about that—that was reported. And nobody talks about it."Even after he beat Cruz out for the nomination, Trump kept calling attention to his claim. "All I did is point out the fact that on the cover of the National Enquirer, there’s a picture of him and crazy Lee Harvey Oswald having breakfast," Trump said while giving remarks in Cleveland, Ohio. As for why Donald Trump references the National Enquirer as a reputable news source? Well, it might have something to do with the fact that Trump's good friend, David Pecker, owns the tabloid. And , as the President "This was a magazine that frankly in many respects, should be very respected. They got O.J. They got Edwards. They got this. I mean, if that was the New York Times, they would have gotten Pulitzer prizes for their reporting."