Alexander Litvinenko died in London in 2006 shortly after being poisoned
Businessman Boris Berezovsky has won damages over claims by RTR, Russian state television, that he was behind the murder of former Moscow agent Alexander Litvinenko.
Mr Litvinenko died in London in November 2006, having fallen violently ill after meeting two Russian men - one a former KGB security officer - at a hotel.
It later transpired he had been poisoned with radioactive polonium-210 and the case caused heightened tensions between the UK and Russia.
The pair had been friends since 1994, when Mr Litvinenko investigated an explosion in Moscow that had killed Mr Berezovsky's driver. Both were to become fierce critics of former President Vladimir Putin's regime.
In court, 63-year-old Mr Berezovsky credited his friend with twice saving his life. In return, he had offered support and financial help.
Mr Litvinenko's widow, Marina, said in evidence that Mr Berezovsky had come to her family's aid when her husband was remanded in custody after unveiling a plot to assassinate the businessman.
Her family had been granted asylum in the UK in 2001, months after Mr Berezovsky began his self-imposed exile.
Both became wanted men in their homeland. Mr Berezovsky was charged with fraud and political corruption in 2001, while Mr Litvinenko was convicted of abuse of office and stealing explosives in his absence in 2002.
So, the court heard, the "outrageous" allegation, made on Vesti Nedeli - described as the equivalent of the BBC's Newsnight - that the oligarch was responsible for the former spy's death came as a complete shock.
RTR offered no evidence that the broadcast was true, while UK police have identified Russian MP Andrei Lugovoi as the prime suspect. Moscow, however, has blocked his extradition.
Mr Berezovsky won £150,000 ($223,800) libel damages
Senior sources have told the BBC they believe the murder had the backing of the Russian state.
Mr Berezovsky has pointed the finger directly at Mr Putin, now the Russian Prime Minister, whose regime he openly admits he would like to bring down.
Yet he was responsible for helping Mr Putin - former head of the KGB's successor, the FSB - rise to power.
A former mathematician, Mr Berezovsky made his fortune by importing Mercedes cars in the 1990s and setting himself up as a middleman distributing cars made by Russia's Avtovaz.
He was among the oligarchs who gained control of Russia's industrial crown jewels at knock-down prices through rigged privatisations, taking ownership of the Sibneft oil firm.
He also became the principal shareholder in the country's main television channel, ORT, which he turned into a propaganda vehicle for Boris Yeltsin, helping to propel him to power in the 1996 presidential election.
A prominent member of Mr Yeltsin's inner circle, he eased Mr Putin's entry into political life by funding the party that formed his parliamentary base.
However, the pair fell out when Mr Putin moved to take control of ORT and to curb the political ambitions of Russia's oligarchs.
Mr Berezovsky left Russia for self-imposed exile in the UK at the end of 2000.
An early attempt to promote opposition to Mr Putin, by funding the Liberal Russia party, ended in disaster when its two most prominent members were assassinated.
He says Mr Putin is prepared to kill anyone that he defines as an enemy of Russia, and that he himself is a target.
That is why the mansion he bought for £10m from broadcaster Chris Evans is equipped with bullet-proof windows, laser monitors, spy cameras and reinforced steel doors.