Swiss forensic scientists have found that the body of Palestinian leader Yasser Arafat contained at least 18 times the normal levels of radioactive polonium, leading to speculation that he was poisoned before he died in 2004.

The 104-page report, prepared by the University Centre of Legal Medicine in Lausanne and published by Al Jazeera, found extremely high levels of polonium in Arafat’s ribs and pelvis, as well as in soil near his body, after his remains were exhumed in November 2012.

Last year, Al Jazeera revealed that the same isotope of polonium was found on Arafat’s belongings at the French hospital where he died, leading to an official murder investigation by the French government. Swiss, French and Russian forensic teams all examined Arafat’s remains as part of the investigation.

Though the French and Russian teams have not yet announced their conclusions, the Swiss report has led many to speculate that Arafat was poisoned in a political assassination.

“Yasser Arafat died of polonium poisoning,” U.K. forensic scientist Dave Barclay told Al Jazeera. “We found the smoking gun that caused his death. What we don’t know is who’s holding the gun at the time. The level of polonium in Yasser Arafat’s rib… is about 900 milibecquerels. That is either 18 or 36 times the average, depending on the literature.”

When Arafat died in 2004, he had spent the past two years inside his Ramallah presidential compound, surrounded by Israeli soldiers. Though Arafat was 75 years old, the Swiss report claims he was “was in good overall health and did not have any particular risk factors.” After eating a meal the night of Oct. 12, however, Arafat quickly fell ill. As his condition worsened, the Palestinian leader was rushed to Paris’ Percy military hospital on Oct. 29. Arafat underwent emergency treatment, but ultimately died from his mystery illness on Nov. 11.  

No autopsy was performed on Arafat, and soon after his death, accusations of foul play abounded, but nothing was proven either way. Now that the polonium findings have been released, however, those close to Arafat have once again declared that the Palestinian Liberation Organization leader was assassinated.

"We are revealing a real crime, a political assassination," Arafat’s widow Suha Arafat told Reuters. “This has confirmed all our doubts. It is scientifically proved that he didn't die a natural death and we have scientific proof that this man was killed."

Researchers specifically found in Arafat’s remains polonium-210, an extremely rare radioactive isotope of polonium. Only about 100 grams of the isotope are produced each year, and only inside the heart of a nuclear reactor, making polonium-210 extremely difficult to procure and handle without the help of a government and trained specialists.

The silver-gray metal emits highly radioactive alpha particles, though they only travel a few centimeters and can easily be blocked by surfaces as thin as a sheet of paper. This means that polonium-210 is not radioactive outside the human body, but once ingested, a 0.1 microgram dose the size of a speck of dust is enough to kill a healthy adult.

Because of the element’s rarity, very few people have died of polonium poisoning. The most famous polonium death was that of former Russian spy Alexander Litvinenko, who died in 2006 in a London hospital after eating a polonium-tainted meal served by killers unknown to this day. According to witnesses, the sudden onset and the slow progress of the Palestinian leader’s disease was similar to Litvinenko’s.

While many are confident that this new information reveals Arafat was poisoned, it is more difficult to determine a motive and possible assassin.

“The main problem is the timeframe,” Barclay told Al Jazeera. “If this was a murder that happened yesterday, you’d have witnesses and cell phone records, emails, bank transfers. In a nine-year-old case that type of information will be hard to obtain.”