Specialists in nuclear, chemical and biological hazards checked Berezovsky's estate in Berkshire for potential threats as part of the ongoing investigation into the tycoon's death. Officials were hesitant to call his death a suicide though unconfirmed reports suggested that was the case.
"It would be wrong to speculate on the cause of death until the postmortem has been carried out. We do not have any evidence at this stage to suggest third-party involvement," said Detective Chief Inspector Kevin Brown.
Berezovsky, 67, was a one-time power broker in Russia who fled the country in 2000 after a falling out with Vladimir Putin. He was later convicted in absentia of embezzling $2 billion from two state-run companies in Russia, the British newspaper The Guardian said Sunday.
Acquaintances told reporters Berezovsky had been depressed recently about personal relationships and an expensive court battle with fellow Russian mogul Roman Abramovich, the owner of Britain's Chelsea soccer club. That was compounded by a former mistress's claim he owed her several million after the sale of a home they shared.
An unnamed friend told The Guardian Berezovsky had talked of suicide and hoped he would die, but doubted he would have gone through with the act.
"He was very, very low. He talked about suicide. He would say to me: 'It's all over, it's all finished, there's no point in anything -- the best thing that could happen to me is that I have a heart attack,' " the friend said. "But I still don't believe he had the courage to take his own life -- he loved life too much."
Notable deaths of 2014 [PHOTOS]
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