Profile: Boris Berezovsky
LONDON, England -- Boris Abramovich Berezovsky was born into a Jewish family in Moscow and studied forestry and then applied mathematics, receiving a doctorate in 1983.
He did research on optimisation and control theory, publishing 16 books and articles between 1975 and 1989, and becoming chair of a laboratory at the Russian Academy of Sciences.
He started out in business in 1989 by buying and selling cars from the state manufacturer AutoVAZ and setting up a new intermediary called LogoVaz in 1992.
Mr Berezovsky became one of the original oligarchs under President Boris Yeltsin, lending money to the state in return for valuable stakes in AutoVAZ, the state airline Aeroflot, and several oil companies which he organised into the giant Sibneft.
Among his associates was Roman Abramovich, now owner of Chelsea football club, although the two are no longer close.
Mr Berezovsky went on to buy media companies including the television channels ORT and TV6, and the newspapers Nezavisimaya Gazeta, Novye Izvestiya and Kommersant which he used to support Yeltsin's re-election in 1996.
He entered parliament himself and became secretary general of the Commonwealth of Independent States which included most of the countries of the former Soviet Union.
He supported Vladimir Putin's campaign for the presidency in 2000.
Soon afterwards he fell out with Mr Putin and moved to Britain, buying a 172-acre estate in Surrey.
He is said to have provided millions of pounds in financial backing for the "Orange Revolution" of Viktor Yushchenko in Ukraine.
President Yushchenko faced opposition from the country's Russian neighbours and survived an attempt to poison him.
Mr Putin launched an attempt to get Mr Berezovsky extradited from Britain over fraud allegations connected with Aeroflot but he was granted political asylum in 2003 on the grounds he had a reasonable fear of persecution.
Alexander Litvinenko alleged in a press conference in Russia that he had been asked by his superiors in the FSB (formerly the KGB) to assassinate Mr Berezovsky.
Litvinenko was later arrested and fled to Britain where he worked for Mr Berezovsky.
He was allegedly poisoned and died later in hospital.