November 2006 - Alexander Litvinenko, KGB defector and author of the book Blowing up Russia, which accuses the Kremlin of masterminding the and Pechatniki and Kashirskoye bombings in order to blame Chechen terrorists and whip up support for an invasion of Chechnya (which shortly followed), is fatally poisoned by radioactive Polonium obtained from Russian sources.
I suspect that there were other reasons or possible reason for Putin to have Litvinenko killed.
What might those reasons be?