The murky source of Roman Abramovich 's vast fortune has been laid bare as part of an extensive investigation into the sanctioned Russian multi-billionaire.
Abramovich, 55, was placed on the UK's sanctioned individuals list last Thursday, resulting in the freezing of his assets and placing huge financial strain on Chelsea, the football club he has owned since 2003.
The oligarch has extensive links with Vladimir Putin, who invaded Ukraine in February in an act of aggression which led to backlash towards wealthy Russians living abroad under so-called 'golden visas'.
Abramovich, along with dozens of his compatriots, has seen his UK assets frozen, including a £150million London mansion and £30million three-storey penthouse.
President Putin's belligerence has led to a fresh wave of scrutiny over oligarchs potentially laundering their money in the UK.
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The BBC launched a probe into the source of Abramovich's wealth four years ago through their Panorama programme, uncovering his substantial links to corruption, theft and alleged kidnapping.
Investigators gained access to a secret five-page document believed to have been smuggled out of Russia which claimed the Saratov native was detained in police custody on suspicion of stealing a trainload of diesel and selling it in 1992.
His lawyers told the BBC the incident was merely a misunderstanding, yet a Moscow police chief launched a warrant for his arrest only for the case to vanish without trace.
The probe then turned its attention to the mid-1990s, when Abramovich made inroads into the Russian energy industry thanks to a rigged auction and a government bribe.
The Chelsea owner planned to combine state-owned oil facilities in Serbia and buy them for a cut-price sum but, given his lack of political influence, needed to curry favour.
Boris Berezovsky, a fellow oligarch, is said to have suggested to Abramovich pay $10million (£7.7m) to a Kremlin official to obtain support. The intended target for the bribe was Alexander Korzhakov, a crony of then-president Boris Yeltsin.
Korzhakov denies there was a bribe but confirmed to the BBC that Berezovsky tried to buy his support.
Regardless of how the money exchanged hands, Abramovich's plan worked and he bought newly-created company Sibneft as part of a rigged auction.
The secret document seen by the BBC also asserts the money he used to purchase the company - which is now known as Gazprom - was borrowed from a bank after a government official deposited $137million (£105m) into an account.
Abramovich bought Sibneft for $250million (£190m) - roughly $2.7billion (£2.1bn) less than it was worth - and would later sell it back to the government for $13billion (£9.9bn) in 2005.
The document shows evidence the Department of Economic Crimes believed Abramovich could have faced charges of fraud for wresting control of Sibneft via the rigged auction.
Remarkably, Abramovich confirmed a number of the claims in the document during a London court case having been sued by Berezovsky once their relationship turned sour.
In the case he won in 2012, he spoke of the payment to the government official and the auction, with judge Lady Justice Gloster finding admissions of corruption, although there were no repercussions in the UK or Russia.
The document is believed to show that, at the time, Yeltsin acted to protect Abramovich by moving files from law enforcement authorities to the Kremlin.
He is also alleged to have stopped an investigation launched by Yuri Skuratov, then the prosecutor general of Russia who would later lose his job after his sex tape surfaced.
Panorama also drew attention to a document from the Spanish authorities which claimed Abramovich - who served as a regional governor under Putin for eight years - manages the president's 'private economic interests'.
This is something Abramovich's lawyers deny, while they also dismissed he was protected by Yeltsin or Putin.
In another dubious transaction in 2002, Abramovich bought oil and gas company Slavneft after there were allegations of a rival negotiator being kidnapped.
Chinese company CNPC was believed to be willing to pay twice as much as its competitors but a representative is said to have been abducted on their arrival at Moscow airport.
CNPC subsequently withdrew their interest and, again, Abramovich purchased the company for a bargain fee in what was described as a pre-arranged sale by Vladimir Milov, Russia's former deputy energy minister.
There is no suggestion Abramovich had any knowledge of the kidnapping and his lawyers insist it did not occur but independent sources confirmed to the BBC it took place.
