The dead billionaire and the 'KGB poison killer'

What killed Badri Patarkatsishvili? As the police scour his home for clues and a pathologist conducts a post-mortem examination, conspiracy theorists will point to the company he kept on the day he died.

On Tuesday afternoon, hours before his death, Patarkatsishvili was with Boris Berezovsky at the law offices of Lord Goldsmith, the former attorney general, in the City.

Berezovsky is at the centre of London-based opposition to Russian president Vladimir Putin's government and on Tuesday he, Patarkatsishvili and their friend Yuli Dubov swore witness statements related to various cases in the former Soviet Union involving seizure of assets and property rights.

Nikolai Glushkov, once Berezovsky's right-hand man, was also there. Glushkov is the man whose story connects directly to the suspect Scotland Yard has named in connection with the murder of former KGB agent Alexander Litvinenko, Andrei Lugovoy.

When Berezovsky fled to London in 2000, Glushkov was arrested on charges of fraud. He had been running Aeroflot, in which Berezovsky had a large stake. Berezovsky believed Glushkov had been thrown into prison to put pressure on him. Glushkov was ill and Berezovsky was afraid he would die in Lefortovo jail, where he was being held. The tycoon hatched a plan, from London, to spring his friend.

It involved an audacious scheme to spirit him away from the prison hospital and the man chosen to carry it out was Berezovsky's trusted former head of security, the former KGB man Andrei Lugovoy.

The escape plot failed and Lugovoy was arrested. Glushkov was eventually freed and came to London, but Lugovoy remained in Moscow where he went on to prosper as head of a large drinks company.

He maintained links with his friends Berezovsky and Patarkatsishvili. When he arranged a meeting in November 2006 with Litvinenko no one was suspicious. But it was at this meeting, Scotland Yard believes, that Litvinenko was given a fatal dose of radioactive Polonium 210, from which he died an agonising death.

Berezovsky and Patarkatsishvili found it hard to believe the man they trusted was the assassin. Patarkatsishvili never believed it. He remained on friendly terms with Lugovoy until his death and spoke to him on the telephone a week ago.

Even if a post mortem reveals Patarkatsishvili died from a heart attack, if there is no evidence of long-term heart disease police inquiries are likely to continue. This is because a number of compounds known to be used by the former KGB can induce heart failure, but leave virtually no trace. One is sodium fluoroacetate, a fine white powder derived from pesticide.

It causes irregular heartbeat and breathing difficulties before a fatal heart attack. Patarkatsishvili had difficulty breathing a few hours before he died and left a meeting to go outside for fresh air.

But Patarkatsishvili's sudden and so far unexplained death raises a question - was he too trusting? If Scotland Yard is right about Lugovoy, it suggests that the attempt to spring his former master's friend from jail may not have been all it seemed.

Did he go through with it - and the subsequent arrest and trial - as a smokescreen to cover the fact he was really working for his old bosses at the KGB? Lugovoy, with his access to first Berezovsky and latterly Patarkatsishvili would have been a valuable asset in the silent war against the London-based exiles. He has always denied any wrongdoing, but Russia refuses to extradite him to stand trial in Britain for the Litvinenko murder.

Patarkatsishvili was the fourth musketeer in a band of men sworn to fight Putin. Dubov is the exuberant writer who wrote a novel based on Berezovsky's exploits. It was made into a film, Tycoon, one of Russia's biggest box office successes.

The band of London-based exiles has infuriated the Kremlin. So what are they up to? The answer is revolution.

Berezovsky and Patarkatsishvili made billions in the smash-and-grab Yeltsin years when Russian state monopolies were privatised. They were among the first to see the opportunities in taking over industries rich in resources, but - at least by western standards - poor in management and exploitation.

Patarkatsishvili was an economics graduate who ran state enterprises before he began a business empire that was to take in a bank, a TV station and numerous other interests.

Berezovsky was a mathematics professor who started his career selling household goods. He moved on to cars and, as capitalism gradually supplanted the Soviet command economy, ran a huge conglomerate, Logovaz.

This was his powerbase and, incidentally, a starting point for his young protégé Roman Abramovich, the owner of Chelsea Football Club, the friend who was to become a bitter rival.

As Berezovsky and Patarkatsishvili acquired huge wealth, Berezovsky sought to expand his influence and power in the Kremlin. The two men picked out a young KGB officer - Putin - who had done well in St Petersburg. With the sponsorship of the two oligarchs Putin rose to be first head of the all-important security apparatus and then Boris Yeltsin's successor as president.

But the tycoons' plans went awry when Putin, instead of being the placeman they intended, began creating his own impregnable political structures, based on resurgent nationalism and a return to state control over major industries such as oil and gas.

Berezovsky and his friends would say there was also a return to the old KGB methods. They were accused, one by one, of fraud or robbing state institutions.

Berezovsky escaped to London after his car was blown up and his driver killed. He still bears the scars of the attack. Dubov, also accused of fraud after amassing his own fortune, was granted political asylum in Britain by David Blunkett, then home secretary, in 2003 at the same time as Berezovsky.

This was when the group of exiles began to coalesce. Akhmed Zakayev, the Chechen actor and friend of Vanessa Redgrave described by Moscow as a terrorist, successfully fought extradition proceedings and remains in London.

Litvinenko sought refuge under Berezovsky's mantle when his former KGB bosses turned on him.

Elena Tregubova, the brilliant journalist and author who angered the Kremlin with her books, fled to London after a bomb exploded at her Moscow flat.

Patarkatsishvili, accused of various fraud offences by the Kremlin, returned to his native Georgia, but bought a home in Surrey, the £10 million Downside Manor outside Leatherhead. He installed his wife Inna and two daughters - both in their twenties - in the property which has a main house and other homes in the grounds. Police have sealed off the site as they check for clues to his sudden death.

Like Berezovsky, who has escaped at least two assassination attempts in London according to police sources, Patarkatsishvili was in fear of his life. That is hardly surprising, when you consider what he and his friend were up to.

Apart from their opposition to Putin, Berezovsky and Patarkatsishvili were active in sponsoring the anti-Moscow Orange Revolution in Ukraine.

Only they know what they spent on organising student protests and activist cells, pumping money into publications, printing equipment and IT equipment but estimates suggest Berezovsky alone put in more than £10 million.

When Viktor Yushchenko took power in 2005 on a tide of revolutionary fervour, Putin was rattled. Despite his personal backing for the pro-Kremlin candidate, he had been beaten in his own backyard. And his old enemies Berezovsky and Patarkatsishvili were among those who made it happen.

Then Patarkatsishvili shifted his attention to Georgia. He stood for president in last month's elections, without making significant impact, but he also sought to recreate the Rose Revolution that swept Eduard Shevardnadze from power in 2003.

This time, he wanted to get rid of the current president Mikheil Saaksishvili, who accused him of plotting a coup and issued a warrant for his arrest.

Patarkatsishvili's death may have been caused by a heart attack, prompted not by an assassin but ordinary ill health.

But he was at the centre of a dangerous game and if he was a casualty, he is unlikely to be the last.