In 1988, he successfully completed the highest level military courses of the KGB USSR counter-intelligence; from 1991 he worked in the Central Staff of the MB-FSK-FSB of Russia, specialising in counter-terrorist activities and infiltration of organised crime.

In 1994 he was put in charge of the FSB part of an investigation of the attempted assassination of influencial enteprenuer Boris Berezovsky.

From this point on, by the direct commission of the FSB, Litvinenko was in regular contact with Berezovsky.

In 1998, Litvinenko and a few more FSB agents were given an order to assassinate Berezovsky. It seemed that FSB chiefs could not imagine that many of their young officers had started to believe in Yeltsin's democratic reforms and so would be reluctant to carry out this order.

Therefore, on November 18th 1998, along with a few of his colleagues, Litvinenko appeared in an unprecedented press-conference, where they reported the planned assassination of Berezovsky. Due to the scandal, FSB director Kovalev was fired and his position was taken by Vladimir Putin. Not long afterwards, Litvinenko was fired as well.

In March 1999 Litvinenko was arrested under the false accusation of having exceeded his authorities. In November 1999, he was acquitted, but right there and then in the courtroom he was arrested again by the FSB and charged with another false accusation.

In 2000 the second criminal case was also closed due to lack of evidence, but later that day the third criminal case against him was opened. This time he was not jailed but had to sign a warrant that prohibited him from leaving the country.

Concerned for his wife and child, in October 2000 he, along with his wife and six-year old son Anatoly, fled Russia to England, where his family was granted political asylum.

Alexander Litvinenko became one of Putin's most vocal critics. He criticized the corruption within the FSB, headed at that time by Putin. Afterwards, he investigated the FSB and Special Forces' involvement in the Moscow apartment bombings of the autumn of 1999, and thus he became one of the most professional and outspoken critics of Putin's regime. He conducted tens of investigations linking Russian FSB and Special Forces agents to murders, genocide in Chechnya and crimes against humanity. All his findings are described in his books: " Blowing Up Russia: The Secret Plot to Bring Back KGB Terror" (co-author with Yuri Felshtinsky) and "Lubyanka Criminal Group", and also in his many published articles.

In July 2006, Putin signed a bill, authorizing Russia's Special Forces to assassinate any of "Russia's enemies" in any country of the world. It enabled Putin, without any sanctions or punishment, to eliminate his critics, a development that caused obvious concern to those with political asylum abroad such as Alexander Litvinenko.

This concern became more pressing after the assassination of journalist Anna Politkovskaya who harshly criticized Putin personally. She was gunned down in her Moscow apartment lobby, and the perpetrators have not been arrested to this day.

On November 1st 2006, Litvinenko met with Mario Scaramella, and separately with Andrey Lugovoy and Dmitri Kovtun. That same evening he fell ill and three days later he was hospitalized.

Alexander Litvinenko died on November 23rd in London's University College Hospital as a result of radioactive Polonium-210 poisoning.

In his death statement Alexander Litvinenko accused President Putin of being responsible for his poisoning.