Quite simply, how could he have done it? How could this skinny kid who emigrated to Russia and returned when it got too tough, have pulled it off? How could some wannabe-communist honourably discharged from the Marine Corps, fire three shots in eight seconds using a bolt action rifle. How could that second bullet have struck somebody in the back, exit their neck and then strike a second person’s back and then leave through their chest?

How could this measly nobody have killed the most powerful person in the world, and then calmly boarded a city bus to escape. And he did all this by himself?

More than half-a-century after one of the most infamous events in US history, most Americans don’t believe Lee Harvey Oswald, an employee at the Texas School Book Depository in Dallas, killed President John F Kennedy - at not least by himself.

A recent survey commissioned by the FiveThirtyEight news site, found that all these years on from that morning on November 22 1963, only 33 per cent of people believe the finding of the official Warren Commission, which concluded in 1964, that Oswald alone was responsible for Kennedy death. A total of 61 per cent believe at least one other person was involved.

But these bare statistics don’t do justice to the colourful waterfall of things people believe did take place that day on Dealey Plaza as JFK and his wife, Jacqueline, drove through the streets, accompanied by Governor John Connally and his wife Nellie.

Indeed, there are probably few events in history that have attracted more alternative theories as to what happened. Some are wild, others seek to follow logic. Thousands of books have been written to promote their author’s beliefs, there have been movies and documentaries. There is an entire conspiracy theory industry that continues to thrive from the death of the nation’s 35th president.

To cite them all would require a large digital file, but among those most commonly asserted are that Kennedy was killed by Lyndon Johnson, the Russians, the Cubans, Cuban Americans, the mafia, the US military, the CIA, the FBI or the “military industrial complex”. The telling of these stories involve the reader to get to know a host of characters, including “Badge Man”, “Umbrella Man”, the “Three tramps” and “Babushka Lady”.

What gives these conspiracies such life, is that there would have been plenty of motives for a plot to kill Kennedy. Lyndon Johnson became president as a result of what happened, Kennedy and the CIA had just tried to overthrow Cuban leader Fidel Castro, Kennedy’s brother, Robert Kennedy, who was himself assassinated five years later, was leading a crackdown against the mafia as his brother’s Attorney General.

As Gerald Posner, a debunker of conspiracies and author of the exhaustive Case Closed, a 1993 book that argues convincingly that Oswald acted alone, says: “This is not a case where the conspiracies appear groundless. In the Arab world there are theories that abounding that 4,000 Jews got the call not to go to work on 9/11, but this is not like that; there are plenty of reasons for people to believe in a conspiracy: you have a guy who spent time in Russia, who was interested in Cuba. And then he was shot two days later by someone who has low-level links to the mob.”

We all know people are willing to believe all sort of things if it suits their purpose or reinforces some fundamental belief. People such as Cliven Bundy and members of other militia believe the federal government wants to take their land and their guns, others believe vaccines are dangerous, despite overwhelming medical evidence to the contrary. Some people insist climate change science is a hoax.

And of course Donald Trump, the 45th president, found that plenty of Americans could be made to believe there was no way a man whose middle name was Hussein, could have been born in America.

The assassination of JFK – in pictures Show all 8 1 /8 The assassination of JFK – in pictures The assassination of JFK – in pictures President John F. Kennedy and his wife Jacqueline Kennedy ride with secret agents in an open car motorcade shortly before the assassination, 22 November 1963 Getty The assassination of JFK – in pictures President John F. Kennedy and his wife Jacqueline Kennedy prior to his assassination Keystone/Getty The assassination of JFK – in pictures Kennedy is struck by an assassin's bullet as he travels through Dallas in a motorcade In the car next to him is his wife Jacqueline and in the front seat is Texas governor John Connally Three Lions/Hulton Archive/Getty The assassination of JFK – in pictures The view from the sixth floor window of the Texas School Book Depository in Dallas, from which Lee Harvey Oswald is thought to have assassinated Kennedy. This photograph was taken approximately one hour after the assassination Hulton Archive/Getty The assassination of JFK – in pictures Lee Harvey Oswald during a press conference after his arrest in Dallas. Lee Harvey Oswald was killed by Jack Ruby on 24 November on the eve of Kennedy's burial AFP/Getty The assassination of JFK – in pictures Lyndon B. Johnson takes the oath of office as President of the United States on the day of Kennedy's assassination. Jackie Kennedy is stood next to Johnson Getty The assassination of JFK – in pictures Kennedy's funeral procession goes into Arlington Cemetery in Washington Newsmakers/Getty The assassination of JFK – in pictures Kennedy's casket sat in the East Room of the White House Newsmakers/Getty

For all of that, cold rational examination of the facts leads to the conclusion that Lee Harvey Oswald acted alone when he killed Kennedy using a Mannlicher-Carcano rifle he bought by mail-order for $12.78. Forensics experts have shown how that second bullet - the so-called “magic bullet”, which never shed its full metal covering - could have struck Kennedy and then gone on to seriously injure Governor Connally. And tests have shown Oswald did indeed have time to fire a third shot that struck the 46-year-old Kennedy in the head and deliver the lethal blow, making his convoy’s race through the streets of Dallas to Parkland Memorial Hospital, a journey in vain.

Furthermore, although a 1979 report by United States House Select Committee on Assassinations concluded there was a second shooter, that was based on an audio that has since been shown to have been recorded after the shooting and did not contain the sound of gunshots.

Kennedy was not a perfect man. He cheated on his wife. His risked nuclear Armageddon with the Russians. Yet the myth that was built around him - even more so after his death - was of a youthful, glamorous leader setting America on a positive, upward path. He literally promised to send a man to the moon.

Against this, you have Lee Harvey Oswald, a man who may have suffered from mental health problems and who was able to easily buy a deadly weapon and kill the man who held the highest office in the land. Given the number of killings and attempted killings involving people with mental health problems, not least the 1981 attempted assassination of President Ronald Reagan, this ought not to surprise us so much.

But back in 1963, people were stunned - by the horror of the event, of the blood and gore stuck to Ms Kennedy’s dress as her dead husband’s successor was sworn in, of the casual nature of the crime, and - essentially - at the lack of balance.