"The analysis showed there was major exposure, and I stress major, to arsenic," said Pascal Kintz, a toxicologist who studied five samples of Napoleon's hair preserved since his death in exile on the island of St. Helena in 1821.
Officially, Napoleon died of stomach cancer. But Paul Fornes, a forensic pathologist who worked alongside Kintz, said that diagnosis was not supported by the autopsy performed on the defeated emperor's body a day after his death.
"The lesions to the stomach described by Francesco Antommarchi (the doctor who performed the autopsy) were not the cause of death," he told a packed conference in Paris.
The research was commissioned by Ben Weider, a Canadian Napoleon enthusiast and a longtime proponent of the theory -- rejected by most mainstream historians -- that the illustrious Corsican was murdered by high-ranking French and British figures because he remained a threat to their power.
Napoleon, who rose swiftly through the ranks of the revolutionary French army, proclaimed himself emperor in 1804. He was exiled a first time to the Mediterranean island of Elba in 1815 before returning for a "Hundred Day" rule that ended with defeat at Waterloo and a second exile.
Weider argued that the British governor of St. Helena, Hudson Lowe, conspired with French count Charles de Montholon to assassinate Napoleon for fear he would escape from the South Atlantic island and return to France.
He said they had been acting under orders from Lord Bathurst, the British minister for the colonies, and the Count of Artois, who later became King Charles X of France.
"If they had killed him suddenly after Waterloo, they would have had a new French Revolution on their hands, because the emperor was very popular. They had to make it look like his health was deteriorating gradually."
"In those days, whoever won the war wrote history. They lied about his death as they lied about his life and achievements. What we are proving today with science is a key to the whole argument."
Both Kintz and Fornes regularly appear as expert medical witnesses at criminal trials in France.
Kintz said he had analyzed Napoleon's hair using atomic absorption spectrophotometry, a technique employed to detect evidence of doping in athletes and drug abuse.
He said the accepted natural upper limit of arsenic concentration in the hair was 1 nanogram per milligram of hair. In one of the samples, that concentration was 38 nanograms.
Kintz rejected suggestions that such a level could have a less sinister cause, such as contamination of local water.
He said the concentration was more than 35 times higher than the average found in the 1990s among a group of 300 people in eastrn France who were tested in the same way after their drinking water was contaminated with arsenic.
But some at the conference expressed doubts whether the hair analyzed was authentic.
"I wouldn't swear all the supposed locks of Napoleon's hair that are scattered around the world these days are authentic," said Baudoin de Witt, a descendant of the emperor.
But the determined Weider plans to ask the French government to open Napoleon's tomb at Les Invalides in Paris to compare the DNA in the hair samples with that of his remains.
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