LONDON (AP) -- British police said Sunday that experts in hazardous materials are searching a property after the death of Boris Berezovsky, the self-exiled Russian tycoon who went from Kremlin kingmaker to fiery critic after a bitter falling out with Russian President Vladimir Putin.
Police said a 67-year-old "believed to be" Berezovsky was found dead at the property in Ascot, a town 40 kilometers (25 miles) west of London on Saturday. Thames Valley police say his death is being treated as "unexplained."
Police said Sunday they have set up a cordon and that officers are conducting the search "as a precaution" and there is no risk to neighbors. The BBC described the site as Berezovsky's home.
"It is important we take all necessary measures to ensure a full and thorough investigation can be carried out," Supt. Stuart Greenfield said in a statement.
Berezovsky — who had survived a number of assassination attempts — amassed a fortune through oil and automobiles during Russia's chaotic privatization of state assets following the collapse of the Soviet Union in the early 1990s.
Once a member of Russian President Boris Yeltsin's inner circle, Berezovsky fell out with Yeltsin's successor, Putin, and fled Britain in the early 2000s to escape fraud charges that he said were politically motivated.
He became a strident and frequent critic of Putin, accusing the leader of ushering in a dictatorship, and accused the security services of organizing the 1999 apartment house bombings in Moscow and two other Russian cities that became a pretext for Russian troops to sweep into Chechnya for the second war there in half a decade.
In recent years, the one-time Kremlin powerbroker-turned-thorn in Putin's side fended off legal attacks that often bore political undertones — and others that bit into his fortune.
Russia repeatedly sought to extradite on Berezovksy on a wide variety of criminal charges, and the tycoon vehemently rejected allegations over the years that he was linked to several deaths, including that of slain journalist Anna Politkovskaya and ex-KGB agent Alexander Litvinenko.
Berezovsky won a libel case in 2010 against a Kremlin-owned broadcaster that aired a show in which it was suggested he was behind the poisoning of Litvinenko, who had fled Russia with Berezovsky's help after accusing officials there of plotting to assassinate political opponents.
He took a hit with his divorce from Galina Besharova in 2010, paying what was at the time Britain's largest divorce settlement. The figure beat a previous record of 48 million pounds ($73.1) and was estimated as high as 100 million pounds, though the exact figure was never confirmed.
Last year, Berezovsky lost a multibillion-pound High Court case against fellow Russian Roman Abramovich and was ordered to pay 35 million pounds ($53.3 million) in legal costs.
Berezovsky had claimed that Abramovich, the billionaire owner of Chelsea Football Club, cheated him out of his stakes in the oil group Sibneft, arguing that he blackmailed him into selling the stakes vastly beneath their true worth after he lost Putin's good graces.
But a judge threw out the case in August, ruling that Berezovsky was a dishonest and unreliable witness, and rejected Berezovsky's claims that he was threatened by Putin and Alexander Voloshin, a Putin ally, to coerce him to sell his Sibneft stake.
It also recently emerged that Berezovsky ran up legal bills totaling more than 250,000 pounds in just two months of a case against his former partner, Elena Gorbunova, with whom he had two children and who claimed the businessman owed her millions.
Earlier this week, The Times of London newspaper reported that Berezovsky was selling property — including an Andy Warhol portrait of the former Soviet Union leader Vladimir Lenin — to settle his debts and pay expenses owed to lawyers.
Cassandra Vinograd can be reached at https://twitter.com/CassVinograd