The death of Boris Berezovsky is yet another turn in the extraordinary story of a man who went from a poorly paid Soviet mathematics professor to a multi-billionaire oligarch in just over a decade.

Rumours abound Berezovsky committed suicide but in the shadowy world of Russian politics and KGB skullduggery authorities are taking no chances.

Specialist officers in chemical, biological, radiological and nuclear substances searched his mansion over the weekend looking for clues to the as-yet unexplained death.

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  • Berezovsky and Abramovich in 2000

    n this Jan. 26, 2000 file photo Boris Berezovsky, left, a controversial business tycoon, and Roman Abramovich, Russian oil tycoon, with reported political connections, both parliament members, walk after the session of the State Duma, parliament's lower house, in Moscow, Russia. They were once said to be like father and son, vacationing, signing deals, and socializing at the Kremlin together. But these days two of Russia's richest men can't stand each other _

  • Boris Berezovsky

    Russian oligarch and businessman Boris Berezovsky at his home in Egham, Surrey, where he lives in exile, 24th August 2002 (Photo by John Downing/Hulton Archive/Getty Images)

  • Russian Media Tycoon Boris Berezovsky

    Russian media tycoon Boris Berezovsky says that he has film footage that proves that Russia's Federal Security Service (FSB) was behind a series of apartment block blasts in Moscow and the city of Volgodonsk in 1999 killing about 300 people creating a pretext for Russia's ongoing war in Chechnya. Russian officials dismissed Berezovsky's allegations and may issue charges and an arrest warrant accusing him of sending money to Chechen rebels. Berezovsky has evaded the charges by moving to London. (Photo by Borys Bierezowski/East News/Getty Images) (AMERICAS SALES ONLY)

  • Boris Berezovsky in 2002

    Russian oligarch and businessman Boris Berezovsky outside his house in Egham, Surrey, where he lives in exile, 24th August 2002 (Photo by John Downing/Hulton Archive/Getty Images)

  • Boris Berezovsky Attends Extradition Hearing 2003

    Russian business magnate and former Kremlin insider Boris Berezovsky wears a mask, showing the face of Russia's President Vladimir Putin, as he leaves Bow Street Magistrates Court April 2, 2003 in London. Berezovsky was arrested in Britain on March 24 after Russian officials sought his extradition on fraud charges. (Photo by Graeme Robertson/Getty Images)

  • (FILES) Picture dated November 1997, sho

    MOSCOW, RUSSIAN FEDERATION: (FILES) Picture dated November 1997, shows Russian presidential candidate Ivan Rybkin (R) and Russian businessman Boris Berezovsky posing in Moscow. Rybkin, whose presidential campaign is financed by Boris Berezovsky, the controversial self-exiled tycoon and President Vladimir Putin's political foe, went missing after he left his apartment in Moscow 05 February 2004 and news of the 57-year-old's disappearance did not become public until the weekend. (FILM) AFP PHOTO / STR (Photo credit should read -/AFP/Getty Images)

  • Berezovsky protests imprisonment of Mikhail Khordorkovsky

    Russian business man Boris Berezovsky stands in front of placards placed at the the Russian Consulate in London 26 May, 2004 calling for the release of his compatriot Mikhail Khodorkovsky. Berezovsky comissioned 100 limousines to drive past the Russian Consulate to demand the release of Khdorkovsky.

  • Member of the pro-Kremlin youth movement

    Member of the pro-Kremlin youth movement Nashi (Ours) dressed as Russian business tycoon Boris Berezovsky poses in front of poster with a portrait of former boss of the Yukos oil company, Mikhail Khodorkovsky, in Moscow, 12 March 2007. A poster reading 'What is it, if not a treason'.

  • Extradition protests 2005

    Supporters of Motherland (Rodina) party hold poster demanding the extradition of businessman Boris Berezovsky from London to Russia during a picket in front of the British embassy in Moscow, 01 March 2005. Berezovsky served as deputy of Russia's security council and was charged by former president Boris Yeltsin with negotiating relations with Chechnya in the late 1990s. After initially backing Vladimir Putin for the presidency in 2000, he had a falling out with the new Russian leader, eventually fleeing to Britain from prosecution for allegedly illegal business activity.

  • Young Guards Protest 2007

    Picture of opposition leader and former Russian Prime Minister Mikhail Kasyanov and exiled Russian multi-millionaire Boris Berezovsky (reads 'Berezovsky, give us some money') lay in a dust container during a pro-Kremlin 'Young Guards of United Russia' movement rally in Moscow, 14 April 2007

  • Protests 2007

    An activist of the pro-Kremlin Young Guards of United Russia movement wears handcuffs and a mask of exiled Russian billionaire Boris Berezovsky during a protest rally in front of the headquarters of the Other Russia opposition movement in Moscow.

  • Marina Litvinenko and Boris Berezovsky

    Marina Litvinenko and Boris Berezovsky at a news conference outside University College Hospital today on the first anniversary of the death of Alexander Litvinenko. Family and friends marked the murder of the outspoken Russian dissident by re-reading his deathbed statement, accusing President Vladimir Putin of complicity in the plot. See PA story POLICE Russia London.

  • Boris Berezhovsky Addresses Frontline Club Audience

    Russian dissident-businessman Boris Berezhovsky is interviewed by BBC foreign correspondent Allan Little during his talk, Insight with Boris Berezovsky: Putting one over Putin, at the Frontline Club on June 6, 2007 in London, England. The controversial oligarch strained UK-Russian relations after recently claiming in an interview with The Guardian that he is scheming to topple Russian President Vladimir Putin. Berezovsky?s links to the poisoned Russian spy Alexander Litvinenko and his campaign against Putin, a man he once supported, have made him a wanted man in Russia. Berezhovsky was one of the Russian oligarchs who acquired massive wealth by taking control of state assets after the fall of communism. Russia has been demanding his extradition to face trial for several years. Britain so far has refused on the basis that he would not get a fair trial in his home country. (Photo by Daniel Berehulak/Getty Images)

  • Demo 2010

    Boris Berezovsky at a demonstration by Stategy 31 outside the Embassy of the Russian Federation, in Kensington, west London. Picture date: Tuesday, August 31, 2010. About 30 people waving placards attended the anti-Kremlin rally in central London which, unlike similar events in Moscow and St Petersburg, passed off peacefully.

  • An activist of the pro-Kremlin youth group Mestnye

    An activist of the pro-Kremlin youth group Mestnye (Locals) carries a cage, containing a picture of Russian oligarch in British exile Boris Berezovsky, reading 'Jail the fraud!', during rally outside the British Embassy in Moscow on January 11, 2011 to support WikiLeaks founder Julian Assange.

  • Roman Abramovitch Takes The Stand As Boris Berezovsky Sues Him For Billions

    Boris Berezovsky leaves The High Court with his partner Yelena Gorbunova on November 2011, where he alleged breach of trust and breach of contract over business deals with Chelsea Football Club owner Roman Abramovich and is claims more than £3.2bn in damages.

  • His Yacht

    Russian billionaire Boris Berezovsky yacht "Thunder B" is seen in the harbor of Golfe Juan, southeastern France, Saturday, Feb. 19, 2011

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