British authorities say chemical and radiation experts found "nothing of concern" after investigating the home of exiled Russian tycoon and Kremlin critic Boris Berezovsky.
The 67-year-old businessman was found dead Saturday at a property in Ascot, a town about 40 kilometers west of London.
Police say they are treating his death as unexplained and that a full inquiry is under way.
Berezovsky had survived at least one assassination attempt in his past, and had lived in Britain since 2000 after falling out with Russian President Vladimir Putin.
Russia had demanded his extradition on charge of fraud, but the British government refused and granted him political asylum.
Berezovsky had made headlines in recent years over various business deals and legal disputes. Last year he lost a legal battle with Russian businessmen Roman Abramovich, also in London, whom he accused of using threats and intimidation to force him to sell shares in the Russian oil company Sibneft at a fraction of their value.
Last week, there were news media reports that Berezovsky had begun to sell personal assets to pay debts related to that lawsuit.
Russian broadcaster Russia Today quoted Berezovsky's lawyer Alexander Dobrinovsky, the head of a Moscow-based legal firm, as saying his client may have committed suicide.