The murder of America’s thirty-fifth president is often regarded as one of the key events in the recent history of the United States. Numerous conspiracy theories have made it appear more complex, and more mysterious, than was in fact the case.

No event in recent American history has been more comprehensively examined than the assassination of President John F Kennedy. Probably none has been been the subject of more demonstrable nonsense, even though it is clear that Kennedy was assassinated by Lee Harvey Oswald. There is no credible evidence that Oswald assisted, or was himself assisted by, anyone else. His own death in police custody was unfortunate, since it prevented a trial in which his motives for shooting first the president, and then a Dallas police officer, might have become clearer. This is by no means certain. During his time in custody, Oswald lied easily and continuously. Had he been tried, he might well have continued to do so. It is noteworthy that almost everyone who knew Oswald well, including his wife and his brother, believed that he was lying about his role in the assassination. Only conspiracy theorists, who did not know him at all, attach much credence to anything he said. Another regrettable aspect of Oswald’s death was that his murder by Jack Ruby inevitably fuelled claims of a conspiracy. It was suggested even at the time that Ruby was some sort of Mafia executioner, charged with keeping Oswald quiet. There is no evidence for this, and much against...