But unlike a public inquiry , it can not hear evidence behind closed doors . 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 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 .