Dec 6 (Reuters) - Following are key details on the main figures in the case of the poisoning of former Russian spy Alexander Litvinenko: * ALEXANDER LITVINENKO: -- Litvinenko served in the KGB's counter-intelligence department and then the Federal Security Service's (FSB) highly secret organised crime group. The FSB is the main successor to the KGB and deals with internal threats. -- In 1998, he turned on his former comrades and said at a Moscow press conference that senior FSB officers had planned to murder Russian tycoon Boris Berezovsky. -- He was arrested several times by the FSB, but was freed by a court and charges were dropped. In 2000 he fled to Britain with his wife and son and was granted asylum, and eventually citizenship. -- Litvinenko co-authored a book in 2002 entitled "Blowing up Russia: Terror from Within", in which he alleged FSB agents co-ordinated apartment block bombings in Russia in 1999 that killed more than 300 people. In 2002 Russia's FSB approached Britain with a request to question Litvinenko in connection with the 1999 bombings. -- He met several contacts on Nov. 1. He was admitted to a London hospital on Nov. 3 with what was diagnosed as radiation poisoning and died on Nov. 23. * MARIO SCARAMELLA: -- Scaramella, a little-known Italian KGB expert, has been poisoned by the same radioactive substance, polonium 210, that killed Litvinenko. -- Scaramella helped advise the Italian parliament's Mitrokhin Commission, which probed the revelations of Vasili Mitrokhin, a senior Soviet archivist during the Cold War who defected to Britain in 1992. The commission had alleged former Soviet Union leaders were behind the assassination attempt against Pope John Paul II in 1981. -- Had a meal at a London sushi bar with Litvinenko on Nov. 1 after which the Russian fell ill. ANDREI LUGOVOY and DMITRY KOVTUN: -- Lugovoy was an officer in the KGB state security service from the late 1980s when he was in charge of protecting senior Soviet officials and later training recruits into the Kremlin guard. He left the state security service at the end of 1996. -- Lugovoy met Litvinenko at a London hotel on Nov. 1 but has denied any involvement in Litvinenko's death. -- A Russian business partner of Lugovoy, Dmitry Kovtun also met Litvinenko on Nov. 1. BORIS BEREZOVSKY: -- A Russian millionaire and implacable Putin critic now living in London. Litvinenko mixed with some of the Kremlin's adversaries including Berezovsky. -- Berezovsky was a mathematician who went into business when Communist rule ended and rose to become a Kremlin power-broker under Russia's first post-Soviet president, Boris Yeltsin. He played a major role in securing his 1996 re-election against a Communist opponent. -- For years in the Kremlin inner circle, he fell out with Putin soon after his election. Faced with charges of corruption, Berezovsky fled to Britain where he was granted political asylum.
