The first CT scans to examine the king’s mummy reveal a cut to the neck deep enough to be fatal.
The secret has been hidden for centuries by the bandages covering the mummy’s throat that could not be removed for preservation’s sake.
The work may end at least one of the controversies surrounding his death.
Precisely how he died has been hotly debated by historians.
Ancient documents including the Judicial Papyrus of Turin say that in 1155BC members of his harem attempted to kill him as part of a palace coup.
But it is less clear whether the assassination was successful. Some say it was, while other accounts at the time imply the second Pharaoh of the 20th dynasty survived the attack, at least for a short while.
Story: Michelle Roberts, BBC News | Photo: Wikimedia Commons