Alexander Litvinenko: Ex-KGB agent and FSB lieutenant-colonel (1962-2006)

Later he was a dissident and writer who was later poisoned and killed in 2006.

In September 2021, the European Court of Human Rights ruled that Russia was responsible for Litvinenko's poisoning.

Litvinenko worked for the KGB and the FSB through the 1980s and 1990s. Later, he accused his bosses of planning to assassinate Russian billionaire Boris Berezovsky. As a result, he was arrested, but later released by Russian authorities. Afterwards, he fled to the United Kingdom and was given British citizenship.

While he was in Russia, Litvinenko tried to publish a book in which he said President Vladimir Putin rose to power with help of the FSB. He said the FSB tried to cover this up by frightening Russians by bombing apartment buildings in Moscow. He said the FSB then pinned the blame on terrorists operating from Chechnya.

On 1 November 2006, Litvinenko suddenly became sick and was hospitalized. He died in London three weeks later, as a result of poisoining by polonium-210. The news of his death spread around the world, and many felt the poisoning was done by the Russian government. Vladimir Putin and Kremlin spokesmen have repeatedly denied this, and many new leads have been taken upon during the case. Although there are some suspects and theories in the murder, no official arrest has been made yet.

Unlike most common radiation sources, polonium-210 emits only alpha particles. These do not penetrate even a sheet of paper or human skin. Thus they are invisible to normal radiation detectors. Hospitals only have equipment to detect gamma rays. Both gamma rays and alpha particles are classified as ionizing radiation, and can cause radiation sickness.

An alpha-emitting substance can cause damage only if taken in (as food or drink) or inhaled (breathed in). It acts on living cells like a short-range weapon.^p327 Litvinenko was tested for alpha-emitters using special equipment only hours before his death.

• Boris Berezovsky