Princess Diana's death Led by Mohammed al Fayed, the allegation is that a pregnant Diana was murdered on the orders of the royal family. A British police investigation and a forthcoming inquest are unlikely to end the speculation.

Princess Diana's death
Led by Mohammed al Fayed, the allegation is that a pregnant Diana was murdered on the orders of the royal family. A British police investigation and a forthcoming inquest are unlikely to end the speculation.

Apollo moon landings
Dodgy shadows, flags waving with no wind and film inconsistencies have led to accusations that some or all elements of the Apollo moon landings were faked by Nasa.

Marilyn Monroe's death
The actress was found dead on August 5, 1962. Her death was ruled to be an overdose and a "probable suicide". But that has not stopped claims that she was murdered. The most recent formal re-investigation uncovered no evidence of foul play, but did conclude that the original investigation into her death had not been conducted properly.

UFO landing at Roswell
Intense speculation has surrounded the recovery of "suspect materials" near Roswell, New Mexico, in 1947. The US military says what was recovered was the debris of a top-secret research balloon which had crashed. UFO proponents believe the wreckage was of a crashed alien craft.

Assassination of JFK
The biggest of the lot. Everyone remembers where they were when they heard US President John F Kennedy, pictured, had been shot dead in 1963. But who really killed JFK that day remains an unanswered question: Lee Harvey Oswald or those men on the grassy knoll?