Glushkov was a close friend and business associate of Boris Berezovsky, the Russian oligarch who was found dead at his ex-wife's home in 2013.
"The death is now being treated as an unexplained".
In recent years, Glushkov lived in the United Kingdom as he had been granted political asylum there in 2010.
Sky News' home affairs correspondent, Mark White, said Mr Glushkov's home in New Malden, southwest London, is being treated as a crime scene.
Counter-terrorism police are investigating the death of a Russian exile who was friends with the late oligarch Boris Berezovsky, who famously fell out with Russian president Vladimir Putin.
Without confirming the man's name, London's Metropolitan police said the counterterrorism command unit was leading the investigation into the death "as a precaution because of associations that the man in believed to have had".
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After Mr Beresovsky was found hanged at his home near Ascot in Berkshire in March 2013, Mr Glushkov told The Guardian he would "never believe" his friend took his own life.
In the 1990s, Glushkov worked for the state airline, Aeroflot, along with Berezovsky's LogoVaz vehicle company.
His family feared he might have been murdered by enemies in Russian Federation, but British police and forensic experts concluded Berezovsky had committed suicide.
Litvinenko died after being poisoned with Polonium-210 in London in 2006, while Georgian businessman Patarkatsishvili was killed in Leatherhead in 2008. He concluded: "I don't see anyone left on it apart from me".
He added: "too many deaths [of Russian emigres] have been happening".
"The death is now being treated as an unexplained", said London police."There is no evidence to suggest a link to the incident in Salisbury".