The former senior official of Russian airline Aeroflot was living in exile in Britain.
A Russian businessman who was associated with a prominent critic of the Kremlin has died in London, his lawyer said yesterday. "[But] I don't believe it was suicide", Glushkov said.
The Metropolitan Police says that its counterterrorism unit is handling the case "because of associations that the man is believed to have had". However, next of kin have been informed.
In the 1990s, Glushkov was director of the Russian state airline Aeroflot and Berezovskys LogoVAZ auto company.
Berezovsky fled to Britain in the early 2000s and sought political asylum for what he claimed were politically motivated fraud charges.
Neighbour Patricia Egan said Mr Glushkov had lived there for several years, describing him as well educated and a lovely fellow.
After his friend Berezovsky was found dead in 2013, Glushkov told the "Guardian" that he doubted that was a result of natural causes.
Of the Skripal case, British Foreign Secretary Boris Johnson said, "the use of this nerve agent would represent the first use of nerve agents on the continent of Europe since the Second World War". I have quite different information from what is being published in the media.
Mr Glushkov was arrested in 1999 and put on trial for allegedly embezzling $7m from Aeroflot, and sentenced in 2004 to three years, three months in prison.
The airline went on to pursue the case in London and Glushkov was due to attend a hearing on Monday morning at Londons Commercial Court but failed to appear.
Russia's Kommersant newspaper quoted Glushkov's family saying that the body carried "traces of strangulation".
Prime Minister Theresa May told parliament Britain would expel 23 Russian diplomats and freeze Russian state assets wherever there was evidence of a threat as part of measures against Moscow which she blames for the poisoning of Sergei Skripal.
In a phone-call with British Prime Minister Theresa May today, US President Donald Trump assured the United Kingdom of support in the case.
Another neighbour who did not want to be named said: "He used to say hello in the street and he came to give our children gifts at Christmas, he was a nice man". The father and daughter remain in critical condition, and British Prime Minister Theresa May has demanded answers from Russian Federation about how the lethal Novichok nerve agent came to be used on United Kingdom soil.