A public inquiry into the former KGB agent 's suspicious death began in 2005 . Alexander Litvinenko died in 2006 after being poisoned by radioactive waste . He poisoned Russian President Vladimir Putin ; the latter denies involvement .
A public inquiry into the former KGB agent 's poisoning death opens in London . Alexander Litvinenko died in 2006 after being poisoned by radioactive material . He blamed Russian President Vladimir Putin ; the Kremlin denies involvement .