Who killed JFK? The Kennedy conspiracy theories explained

With stories about the CIA, aliens and the Illuminati, those shots are continuing to reverberate across the US

As the 99th anniversary of John F Kennedy's birth approaches, new and outlandish conspiracy theories surrounding the US president's death continue to surface.

It was all over in a few seconds, but his assassination on 22 November 1963 has generated five decades of "painstaking, and for some unsatisfying, analysis", the Daily Mail says.

Five years ago, a team of historians and retired Secret Service officers used the latest digital technology to analyse all the available film and still images taken in Dallas that day. Their conclusion: a "categorical confirmation" that JFK's assassin, Lee Harvey Oswald, acted alone.

Despite numerous FBI investigations and government commissions, many still refuse to accept the official version of events. Here are the topics that have triggered the most debate:

The 'magic bullet' theory

Oswald fired just three bullets in Dallas. But he killed JFK and badly wounded Governor John Connally who was sitting in the front seat of the limousine. The Warren Commission - the investigation into JFK's killing set up in 1963 - came up with the 'single-bullet theory' to explain how Oswald did so much damage with just three rounds. It posits that both men were hit by a single bullet which "entered JFK's upper back, exited his throat, and then struck Connally, breaking a rib and shattering his wrist, and finally coming to rest in his thigh," says the Mary Ferrell Foundation. Sceptics say the trajectory was fanciful and re-named it the 'magic bullet theory'. It's just one reason why conspiracy theorists think more than one shooter was involved.

The grassy knoll

Most JFK conspiracy theories pivot around the idea that Oswald wasn't acting alone. When the president was hit by the bullet that killed him, the motorcade was passing a grassy knoll on the north side of Elm Street. Newspaper photographs record that shortly after the shooting, police arrested three tramps found in a railroad car behind the knoll. Because the men were clean-shaven and well dressed there was speculation that they were CIA assassins rather than hobos.

Rafael Cruz

Earlier this month, Republican presidential hopeful Donald Trump insinuated that Senator Ted Cruz's father was connected to the assassination. His comments were based on a photo published by the National Inquirer, which the tabloid claims shows Rafael Cruz distributing leaflets with Oswald just months before he murdered the president.

Trump seized on the story to attack his then-rival, saying: "I mean, what was he doing – what was he doing with Oswald shortly before the death? Before the shooting?" The story, and Trump's comments, were quickly rubbished by Cruz and the press. "Now let's be clear: This is nuts. This is not a reasonable position. This is just kooky," Cruz told USA Today. "I guess I should go ahead and admit yes my dad killed JFK, he is secretly Elvis and Jimmy Hoffa is buried in his backyard."

The long list of culprits

If Oswald was a paid assassin rather than a disaffected loner, who was writing his pay cheques? The list of candidates is long, but some names are put forward more than most. They are:

The CIA: The idea that the assassination was a CIA plot sounds bizarre, but conspiracy theorists suggest the president's alleged comment that he wanted to "splinter the CIA into a thousand pieces and scatter it to the winds" made him an agency target. Other theories suggest that one of the tramps (see above) was E Howard Hunt, a former CIA operative who was involved in the ill-fated Bay of Pigs operation to oust Cuban leader Fidel Castro.

The Mafia: Why would the mafia want JFK dead? Because his brother, Robert, was turning up the heat on organised crime. Robert was the US attorney general at the time and his "anti-mafia crusade" had lead to a sharp increase in the number of prosecutions of senior mafia figures.

The KGB: "The Soviets had a palpable, powerful motive [to kill JFK]: to gain revenge for the humiliation of the USSR in the 1962 Cuban missile crisis," says Scienta Press. Oswald was a communist and had spent time in the USSR. His "Russian odyssey" afforded the KGB "many opportunities to interact with him".

Lyndon B Johnson: In 2003, a Gallup poll revealed that 20 per cent of Americans believed Johnson had something to do with JFK's death. Theories include the vice president's "desire to become president, his need to cover up scandals, and his involvement with the FBI", says the Environmental Graffiti website.

The Little Green Men: Another theory suggests JFK was killed for showing too much interest in "alien activity". There are two "crucial" pieces of evidence backing this up. The first is a letter written by JFK to the CIA in which he demands to see secret UFO files. The second is a note from a senior CIA official that says "we cannot allow" the president to see the classified material.

The Illuminati: The secretive powerbrokers who control the world are obvious candidates for a JFK conspiracy theory. The president fell foul of the Illuminati, it has been suggested, because he wanted to end the Vietnam War, a conflict that was paying the "shadowy bankers" handsome dividends. The Illuminati were also "angered" by JFK's attempts to "rein in" the power of the US Federal Reserve, triggering a deadly backlash.

Jackie Kennedy: One of the more far-fetched theories alleges that JFK's wife killed him herself. Could the president's wife have been a secret assassin? Some theorists claim that Jackie Kennedy hid a pistol in a nearby flower pot after the assassination. But, as the Daily Mirror notes, "many of those who make the claim seem to overlook the fact that she was being watched in an open limousine by thousands of onlookers".

The man with the black umbrella: Some witnesses point to a "mysterious" man holding an umbrella as JFK's motorcade drove by. The day of the assassination was bright and clear; no one in the crowd is wearing a raincoat or carrying an umbrella except one man. And that man is standing right where the shots were fired.

Investigator Josiah Thompson says: "The only person under any umbrella in all of Dallas [is] standing right where the shots come into the limousine. Can anyone come up with a non-sinister explanation for this?"

When challenged to explain himself, the man carrying the umbrella, Louie Steven Witt, testified before the house select committee on assassinations that the umbrella was a protest against the appeasement policies of JFK's father. The umbrella was a reference to the trademark accessory of Neville Chamberlain, nicknamed the Umbrella Man, who prior to the Second World War had advocated making concessions to the Nazis to try to avoid conflict. Many accepted Witt's explanation.

The driver: Proponents of this theory suggest secret service agent William Greer, the driver of JFK's limousine, pulled the trigger. But others, including JFK Lancer, say that what initially looks like a handgun when seen at speed is simply the reflection of the sun on Greer's colleague Roy Kellerman's hair.

Friendly fire: Not all sceptics rely on elaborate conspiracies to explain the killing. A simpler alternative suggests that one of JFK’s own bodyguards fired the fatal shot by accident. As Oswald fired on the president, the theory goes, Secret Service agent George Hickey cocked his automatic rifle to return fire. When the car he was in stopped suddenly, he discharged his weapon by mistake. "It's not sexy. It's not rife with intrigue," Bonar Menninger, a journalist and proponent of the theory, told NBC News. "But for that reason, in my mind, it's extremely compelling - because it's the only theory that hews tightly to the available evidence." Hickey sued for libel in 1995, but a judge ruled that the statute of limitations had passed and dismissed the case.

What have declassified documents revealed?

Nearly 19,000 pages of top secret government documents from the Cold War era were recently released by the CIA - and many were hoping they would shed some light on the lingering mystery.

The papers marked 'for the president's eyes only' revealed how Oswald planned to escape, confirming rumours that he visited the Cuban and former Soviet Union embassies in Mexico City in September that year.

Intelligence chiefs believe this was to arrange for visas so that he could travel to the USSR via Havana. "But conspiracy theorists looking for CIA plots are likely to be disappointed as many of the intelligence briefs remain partially blacked out," Sky News points out.

One historian who has been researching the trove of declassified documents hopes to put some of the wild theories about JFK's assassination to rest.

"I've gone through each of the conspiracies one by one, trying to line them up, and could just never make [them] jump," Timothy Naftali told The Guardian. "I believe it was Lee Harvey Oswald [who killed Kennedy]."

Could JFK have survived?

For all the competing conspiracy theories, there is a remarkable accepatance of one point: President Kennedy did die on 22 November 1963. "Not even the crankiest crank argues that JFK is hiding out in a Boca pad with Jimmy Hoffa and DB Cooper," says Vanity Fair.

But on this point too there is room for disagreement on the details. Some believe that the president was still alive when he arrived at Parkland Hospital; others that he was dead before the final shot had been fired. Establishing the precise moment of his death is difficult, not only because of the chaos in the aftermath of the shooting, but also because there is no clear-cut definition of life and death in cases such as JFK's.

"The time [of death] was fixed at 1pm, as an approximation," the Warren Commission stated, "since it was impossible to determine the precise moment when life left the President."

The report suggested that JFK could have survived the neck wound caused by the first shot, but not the brain damage that resulted from the second. "From a medical viewpoint, President Kennedy was alive when he arrived at Parkland Hospital," it said. "The doctors observed that he had a heart beat and was making some respiratory efforts.  But his condition was hopeless, and the extraordinary efforts of the doctors to save him could not help but to have been unavailing."

What happened to Lee Harvey Oswald?

Less than an hour after Kennedy was assassinated, a police officer named JD Tippit stopped Oswald, who shot him at point blank range. Oswald, a 24-year-old former marine who had defected to the Soviet Union and returned to the US with a Russian wife the previous year, was later apprehended at a nearby cinema.

Two days later, when he was being transported from police headquarters to a more secure county jail, Oswald himself was shot. Jack Ruby, a nightclub owner, emerged from a crowd of police and reporters, who had gathered to see Oswald taken away, and fired a pistol into his stomach. Oswald was taken to Parkland Hospital and died just ten feet away from the room where Kennedy had died two days before.

Some believe Oswald was killed in order to stop him from revealing a larger conspiracy theory. Ruby claimed he was so outraged by the president's death that he had suffered "psychomotor epilepsy" and shot Oswald unconsciously. However, he was found guilty of murder with malice. Although he was initially sentenced to die, a court of appeal later ordered a retrial and he died of lung cancer in 1967 before it could be held.