At the time, French doctors said Arafat died of a stroke. According to French records, he had suffered inflammation, jaundice, and a blood condition known as disseminated intravascular coagulation, or DIC.
The records were inconclusive about what brought about the DIC, which has numerous causes including infections, colitis, and liver disease. Outside experts who reviewed the records on behalf of the Associated Press were also unable to pinpoint the underlying cause.
Many in the Arab world believe he was killed by Israel, which held him responsible for the bloody Palestinian uprising of the early 2000s. Israeli officials have repeatedly denied foul play, and they dismissed the latest theories as nonsense.
That debate was reignited after a Swiss lab said Wednesday it had discovered traces of polonium-210 in clothing and other belongings provided by Arafat's widow, Suha. She told the lab that Arafat had used the items in his final days. The development was first reported by the Al-Jazeera satellite channel.
Polonium-210 is best known for causing the death of Alexander Litvinenko, a onetime KGB agent-turned-critic of the Russian government, in London in 2006. Litvinenko drank tea laced with the substance.
Francois Bochud, who heads the Institute of Radiation Physics in Lausanne, Switzerland, told the AP on Wednesday that his lab had discovered "very small" quantities of polonium-210, which is naturally present in the environment. But levels found in blood and urine samples taken from the clothing were well above normal.
He said Arafat's wife told him she had stored the items in her lawyer's office after her husband died. It was not clear why she waited so long to test them.
Bochud stressed that the discovery did not provide proof that Arafat had been poisoned. That would require further testing.