British police gave the all-clear Sunday morning to the home of Boris Berezovsky, who died Saturday of unknown causes. Police said no biological, chemical or nuclear weapons were found at Berezovsky’s property in Ascot, about 25 miles west of London. Berezovsky, one of Russia's first post-Communist oligarchs, was a well-known critic of Russian president Vladimir Putin. He had fled to Britain after bitterly falling out with Putin in 2000, although a Kremlin spokesman said on Saturday that Berezovsky had recently written to Putin asking to return home. Berezovsky, who had survived several assassination attempts, had been a close associate of former KGB officer Alexander Litivenko, who died in 2006 after being poisoned by radioactive material in London.