Former Russian spy, Alexander Litvinenko, 43, is the first known victim to be poisoned with polonium-210 and to die from the resulting radiation sickness. It remains unclear who poisoned Litvinenko, who died on Nov. 23, three weeks after he fell ill in London. On his deathbed, Litvinenko accused Russian President Vladimir Putin of his poisoning. Two days later, The Mail on Sunday published a written statement by Litvinenko, entitled, "Why I believe Putin wanted me dead..." Litvinenko had been investigating the murder of Russian journalist Anna Politkovskaya and the Kremlin's forced takeover of the oil firm Yukos, according to The London Times. On Nov. 1, Litvinenko was in London and held several meetings, including a morning meeting with two former KGB agents and a sushi lunch with an Italian acquaintance, Mario Scaramella. By that night, he had become sick but doctors did not identify his polonium poisoning until his death. Investigators then tested the sites Litivenko had visited on Nov. 1 and found traces of plutonium. Scaramella has since fallen ill with radiation poisoning as Scottish Yard continues to investigate case.