Experts in chemical, biological, radiological and nuclear (CBRN) emergencies have been deployed to the British property where Russian exile Boris Berezovsky was found dead, police said Sunday.
"Specially trained officers are currently at the scene, including CBRN trained officers, who are conducting a number of searches as a precaution," a statement from Thames Valley Police said.
"This is to enable officers to carry out an investigation into the man's death. The body of the man is still in the property at this time."
Berezovsky, a Russian oligarch and long-time critic of Russian President Vladimir Putin, was found dead at his home near Ascot, a well-heeled commuter town near London, on Saturday afternoon.
His lawyer said the 67-year-old had been depressed over his debts and it was likely suicide, but police have cordoned off the mansion and surrounding streets as they investigate a death they are describing as "unexplained".
Berezovsky was friends with another Russian exile and Kremlin critic, Alexander Litvinenko, who died of radioactive poisoning in London in 2006. His widow blames the Russian state.
Superintendent Stuart Greenfield said police were taking "all necessary measures to ensure a full and thorough investigation can be carried out" into Berezovsky's death.
"I would like to reassure residents that we are confident there is no risk to the wider community," he said.