The Metropolitan Police said they have assigned counter-terror officers to investigate the death "because of associations [Glushkov] is believed to have had".
The statement confirmed that police were called by the London Ambulance Service at 22:46 on Monday, to reports of a man found deceased at a residential address in Clarence Avenue, New Malden.
Police were quick to suggest there is now no evidence to link the death to events in Salisbury, where the former spy Sergei Skripal and his daughter Yulia were poisoned with a weapons-grade nerve agent that was only ever produced in Russian Federation.
In 2000, he was arrested in connection with the embezzlement of Aeroflot's funds, and later charged with fraud and money laundering.
Glushkov was best-known for being a close associate of Boris Berezovsky, a Russian oligarch who fled to Britain in the early 2000s after falling out out with Putin. A post-mortem examination will be held in due course.
Glushkov had worked for Russian airline Aeroflot and at Berezovksy's LogoVAZ vehicle company.
In recent years, Glushkov lived in the United Kingdom as he had been granted political asylum there in 2010. "The death is now being treated as unexplained", he said.
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.
Berezovsky was found dead at home in 2013, an incident which had some hallmarks of suicide, but which Gluskhov was adamant was politically motivated. In March 2017, Moscow's Savelovsky District Court handed him a second eight-year sentence in absentia for the embezzlement of Aeroflot's funds.
Authorities said the two are believed to have been poisoned by Novichok, a nerve agent believed to be 5 to 8 times more potent than VX or sarin.