Updated from 11:09 a.m. EDT to include U.K. police statement that no evidence yet suggests a third party was involved in death of Boris Berezovsky.By Cassandra Vinograd, Associated Press LONDON -- There was no evidence to suggest anyone else was involved in the death of Boris Berezovsky, the self-exiled Russian tycoon who went from Kremlin kingmaker to fiery critic, British police said Sunday. With an investigation under way, police are treating the death of Berezovsky -- who fled to Britain in the early 2000s after a bitter falling out with Russian President Vladimir Putin -- as unexplained. But the former oligarch survived assassination attempts and recently faced financial difficulties, prompting speculation as to whether his death was part of a conspiracy -- or suicide. Police said Sunday it would be wrong to speculate on Berezovsky's cause of death pending the results of an autopsy, but said they had no evidence to suggest anyone else was involved. "We are at the early stages of the investigation and we are retaining an open mind as we progress," said Detective Chief Inspector Kevin Brown. "The investigation team is building a picture of the last days of Mr. Berezovsky's life, speaking to close friends and family to gain a better understanding of his state of mind." Police released some details on the circumstances that triggered their investigation into his demise and a subsequent check for hazardous materials at a home he stayed at in Ascot, a town 40 kilometers (25 miles) west of London where Berezovsky's body was found on Saturday. A call came into police from the local ambulance service at 3:23 p.m. GMT (11:23 a.m. EDT) Saturday saying a man had been found dead, Thames Valley Police said in a statement on Sunday. The police said an employee of Berezovsky told how he had called an ambulance after becoming concerned for Berezovsky's welfare and forced open a bathroom door locked from the inside to find the tycoon's body on the floor. The employee was the only person in the house when Berezovsky's body was discovered, police said. Members of the ex-oligarch's family arrived at the home while the paramedic was on scene. After a paramedic declared Berezovsky dead and left the scene, a device measuring the paramedic's exposure to radiation was triggered, police said. This is why chemical and radiations experts were called to examine the home, they said.