The Egyptian "boy king" Tutankhamun may well have died of malaria after the disease ravaged a body crippled by a rare bone disorder, experts say.
The findings could lay to rest conspiracy theories of murder.
The scientists in Egypt spent the last two years scrutinising the mummified remains of the 19-year old pharaoh to extract his blood and DNA.
This revealed traces of the malaria parasite in his blood, the Journal of the American Medical Association says.
Shrouded in mystery
Ever since Howard Carter's discovery of Tutankhamun's intact tomb in the Valley of the Kings in 1922, scholars have speculated over why the 19-year old 'boy king' died so young.
Some believe he was killed by a fall from his chariot. Others suspect foul play.
Because he died so young, and left no heirs, scholars have speculated that, instead, he may have suffered from a disease that ran in his family.
Artifacts have shown the royalty of that era as having a somewhat curvaceous and rather feminine appearance, which some say would be typical of inherited conditions like Marfan syndrome.
But Egypt's chief archaeologist Dr Zahi Hawass rejects these explanations.
He and his team have painstakingly picked over the remains of Tutankhamun and 10 other royal mummies from his family - two of which they have now confirmed using genetic fingerprinting to be the young king's grandmother and most probably his father.
They say there is no compelling evidence to suggest King Tut or indeed any of his royal ancestors had Marfan's - the voluptuous artefacts, they believe, are a red herring and merely reflect the fashion of the time.
But they did confirm that the king may have had some form of inherited disease, a rare bone disorder affecting the foot called Kohler disease II, as well as a club foot and a curvature of the spine.
Although this was not his ultimate downfall, it would explain why among his possessions there were sticks and staves that could have been used as walking canes, say the researchers.
Not long before his death, the king fractured his leg, and the scientists think this was important.
The bone did not heal properly and began to die. This would have left the young king frail and susceptible to infection.
What finished him off, they believe, was a bout of malaria on top of his general ill health.
The scientists found traces of the malaria parasite in the pharaoh's blood - the oldest mummified genetic proof for malaria in ancient populations that we have.
Dr Hawass and his team say: "A sudden leg fracture possibly introduced by a fall might have resulted in a life-threatening condition when a malaria infection occurred.
"Seeds, fruits and leaves found in the tomb, and possibly used as medical treatment, support this diagnosis."
Dr Bob Connolly, a senior lecturer in physical anthropology at Liverpool University, has examined Tutankhamun himself.
He said the researchers had been incredibly lucky to be able to extract the DNA for study.
"His is not a beautifully preserved mummy. It's a charred wreck. Hawass and his team have been incredibly clever and lucky to do this."
He said it was possible that the king died from malaria, but he personally doubted it.
"Just because he had the parasite in his blood does not necessarily mean he suffered from malaria or died from it. It may not have caused him any trouble."
"I still think he died from a fall from his chariot. His chest cavity was also caved in and he had broken ribs."