So it's possible that someone could have planted small amounts of polonium-210 in Arafat's belongings, Dallas said. High levels were found by a team of Swiss researchers at the Institut de Radiophysique.

Even through exhuming the body, it's not clear that detection would be foolproof, Dallas said. As time goes on, there's less and less of the radioactive substance left, so it would be more and more difficult to tell how much polonium-210 Arafat was exposed to, if any.

"It's going to be very hard to determine whether polonium was ever introduced there," Dallas said. "There will be a lot of dispute, I guess, depending on who is incriminated by this."