Nikolai Glushkov, a close associate of late Putin critic Boris Berezovsky, has been found dead in his London home.
The news was confirmed Tuesday on Facebook by Moscow Times board member Damian Kudryavtsev, who was close to both Glushkov and Berezovsky.
It is not yet known how he died but his death has not been linked to the Salisbury poisoning case, the Metropolitan police said.
“At this stage the Met Police Counter Terrorism Command is leading the investigation as a precaution because of associations that the man is believed to have had,” they added.
A post-mortem is due to take place in the coming days.
Glushkov held a top position with Russia’s state airline Aeroflot and worked under Berezovsky in the nineties.
Billionaire and business oligarch Berezovsky later ran afoul of the Kremlin when he publicly denounced Putin and brought a lawsuit against his ally, fellow billionaire Roman Abramovich.
He sold his holdings in Russia and sought refuge in London in 2000 following a fraud investigation into his and Glushkov’s management of Aeroflot.
He was found dead in 2013 of an apparent suicide. His body was discovered in a locked bathroom in his home with a rope around his neck.
"Boris was strangled. Either he did it himself or with the help of someone. [But] I don't believe it was suicide,” Glushkov said in an interview with The Guardian newspaper.
He added: “too many deaths [of Russian emigres] have been happening.”
Berezovsky was also a close associate of Alexander Litvinenko, a former Russian spy who was poisoned and killed in London in 2006. A British public inquiry concluded Russia’s secret service FSB, with Putin’s approval, was probably behind the hit, although Russia denies this.