After working for the KGB and its successor, the FSB, Litvinenko publicly accused his superiors of ordering the assassination of Russian billionaire Boris Berezovsky. He was arrested by Russian authorities and then released; he later fled to the UK, where he was granted political asylum and citizenship.
Litvinenko tried to publish a book in Russia in which he described Vladimir Putin's rise to power as a coup d'état organised by the FSB. He stated a key element of FSB's strategy was to frighten Russians by bombing apartment buildings in Moscow and other Russian cities. He alleged the bombings were organised by FSB and blamed on Chechen terrorists to legitimise reprisals using military force in Chechnya.
On 1 November 2006, Litvinenko suddenly fell ill and was hospitalised. He died three weeks later, becoming a rare victim of lethal polonium-210 radiation poisoning under highly suspicious circumstances. The fact that Litvinenko's revelations about alleged FSB misdeeds were followed two years later by his poisoning led to public accusations that the Russian government was behind his death, resulting in worldwide media coverage.