United Kingdom counter-terror police are investigating the "unexplained death" of a Russian businessman in London.
But he is believed to be Nikolai Glushkov - a friend of the late Russian oligarch Boris Beresovsky, who criticised President Vladimir Putin.
British police, who did not name Glushkov, said that they were investigating the death of a man in his 60s who lived on Clarence Avenue.
Counter-terror police said it was in charge of the probe "as a precaution because of associations that the man is believed to have had", a spokesman said.
There is no evidence to suggest a link to the March 4 poisoning of former spy Sergei Skripal and his daughter, the statement said.
The 68-year-old Glushkov was a businessman in Russian Federation after the fall of Communism and had been a close associate of oligarch Boris Berezovsky, who was forced to flee Moscow after falling out with Vladimir Putin. "A post-mortem examination will be held in due course", the source added. Police said he committed suicide but Glushkov told The Guardian in 2013 that he suspected foul play.
Glushkov came to the United Kingdom after being freed from prison and spoke out against Berezovsky's death claiming he never believed his friend died of natural causes.
Glushkov, whose body was found last night at home in New Malden, South West London, had been caged for five years for money laundering while deputy director of Aeroflot.
Counterterrorism police have been called in to investigate the unexplained death of a 68-year-old Russian exile who had claimed political asylum in the UK.
Glushkov was friends with Boris Berezovsky, a Russian oligarch who died in London in 2013.
He was found dead on Monday night.
Glushkov had said at the time that he did not believe Berezovsky died of natural causes.
In 2017, during a trial in absentia in Russia, Glushkov was sentenced to eight years in prison for stealing $123m from Aeroflot.