Swiss forensic scientists say samples taken from the exhumed corpse of the late Palestinian leader Yasser Arafat show unexpectedly high levels of the lethal radioactive isotope polonium-210.
The findings from specialists at the University of Lausanne were released Wednesday in a 108-page report and posted online by the pan-Arabic television network al-Jazeera. The probe was commissioned jointly by Arafat's widow, Suha, and the network.
Forensic experts from France and Russia also took samples from Arafat's corpse in 2012. Moscow has said its examination found no traces of polonium, while results from the French analysis have not yet been released.
The Swiss document appears to be the most significant evidence so far linking Arafat's death to foul play. But its authors framed their analysis cautiously, saying the results "moderately support the proposition" that the death was caused by polonium poisoning.
The Swiss experts said their analysis took into account the time lapse since Arafat's death and the nature and quality of the specimens examined.
Arafat fell ill in October 2004 and was airlifted to France days later, after he failed to respond to treatment from a team of Mideast medical specialists. In early November, he lapsed into a gradually deepening coma and died November 11.
His death spawned a host of conspiracy theories, with many Palestinians accusing arch-rival Israel of complicity in his death. Israel has flatly rejected the allegations.
In a separate and still controversial 2006 case, British investigators directly linked polonium-210 to the poisoning death of one-time Russian spy Alexander Litvenenko, who had defected to London. Litvenenko, from his death bed, accused Russian President Vladimir Putin of ordering his murder, accusations that were flatly denied by Moscow.
Russia later denied British extradition requests for a key suspect in the case, which remains open.