Palestinian investigators said Israel was the "only suspect" in the death of Yasser Arafat, after results from a Swiss investigation found high-levels of radioactive polonium on the former Palestinian leader's remains."Our efforts are ongoing...to find out who stands behind thedeath of Yasser Arafat and who has the technical and scientificmeans for this. We consider Israel the first, fundamental andonly suspect in Yasser Arafat's assassination," Palestinian inquiry chief Tawfiq Tirawi said.At a press conference in Ramallah, Palestinian officials said the Swiss report shows Arafat did not die from old age or ill health, nor did he die of natural causes. "This is the crime of the 21st century," Tirawi said. "The fundamental [goal] is to find out who is behind the liquidation of Yasser Arafat."He brushed off as "rumors" speculation by some Palestinians that members of Arafat's entourage killed him, saying his committee deals only in facts and evidence.Scientists who conducted tests on samples taken from the body found high levels of radioactive polonium-210 in the ribs and pelvis, as well as in soil that absorbed his bodily fluids.The Russian report was significantly more cautious than the Swiss conclusions, saying they found insufficient evidence to support the theory that Arafat died by polonium poisoning."The outcome of the comprehensive report on the levels of Polonium-210 and the development of his illness does not give sufficient evidence to support the decision that Polonium-210 caused acute radiation syndrome leading to death," said Dr. Abdullah Bashir, quoting the conclusions of the Russian report. But Dr. Bashir said that both the Swiss and Russian reports found "large amounts" of the radioactive isotope in his remains."This substance [polonium] is owned by states, not people, meaning that the crime was committed by a state," PLO official Wasel Abu Yusef told AFP.Israel denied accusations it poisoned Arafat, calling it "nonsense" and a "soap opera."Arafat died in France on November 11, 2004 at the age of 75. Doctors were unable to specify the cause of death and no post-mortem was carried out at the time.Allegations of foul play surfaced immediately. Arafat had foes among his own people, but many Palestinians pointed the finger at Israel, which had besieged him in his Ramallah headquarters for the final two and a half years of his life.Samples were extracted from Arafat's corpse last November by Swiss, French and Russian experts after an al-Jazeera documentary revealed unusually high amounts of the deadly Polonium isotope on his clothes.The results of the French team have yet to be published. The 108-page Swiss report, prepared by the University of Legal Medicine in Lausanne, says there was at least 18 times the normal level of polonium in Arafat’s remains.Prof. Francois Bochud of the Swiss investigation team told a news conference on Thursday that while the high level of polonium detected indicated on involvement of a third party, the results only offer moderate backing of the theory of poisoning."Was polonium the cause of the death for certain? The answer is no, we cannot show categorically that hypothesis that the poisoning caused was this or that," he added. In the wake of the report, PLO and Fatah officials called for an international investigation into the circumstances surrounding the death. While some of these officials pointed a finger at Israel, Arafat’s widow, Suha, told Reuters she was sure that “it’s someone in his close circle.”She quoted an unnamed expert as saying that the poison had been put in Arafat’s tea, coffee or water.Suha also called on Egyptian Defense Minister Abdel Fattah al-Sisi to help find out who killed her husband during a phone interview with Egyptian television channel Dream.Khaled Abu Tomeh contributed to this report.