Litvinenko was poisoned with radioactive polonium-210 in 2006. It is suspected that Russian secret agents committed the murder. They are said to have mixed the polonium into his tea. But Moscow is refusing to allow the extradition of the two main suspects. Litvinenko had broken with the Kremlin and later worked for the British intelligence services. In his deathbed statement, he said he held Russian president Vladimir Putin directly responsible for his murder.