Apparently it's the same Polonium-210 used to kill a guy in London in 2006: <a href="http://en.wikipedia.org/wiki/Poisoning_of_Alexander_Litvinenko" rel="nofollow">http://en.wikipedia.org/wiki/Poisoning_of_Alexander_Litvinen...</a><p>Full Lancet paper here (paywall): <a href="http://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2813%2961834-6/fulltext" rel="nofollow">http://www.thelancet.com/journals/lancet/article/PIIS0140-67...</a>