Alexander Valterovich "Sasha" Litvinenko (30 August 1962 or 4 December 1962 – 23 November 2006) was a British-naturalised Russian defector and former officer of the Russian Federal Security Service (FSB) who specialised in tackling organized crime. A prominent critic of Russian President Vladimir Putin, he advised British intelligence and coined the term "mafia state". He was poisoned in London, believing - as do British authorities - that his killers were FSB operatives.