The Russian political exile Nikolai Glushkov was found dead in London on Monday night.
The British police say he was murdered, killed by a compression to the neck.
The 69-year-old previously said he was on a Kremlin hit list.
The Russian exile opposed to Russian President Vladimir Putin who was found dead in London earlier this week was murdered, the British police say.
Nikolai Glushkov, 69, was found dead at his house in southwest London at about 10:46 p.m. on Monday. A subsequent pathologist report found that Glushkov died by a "compression to the neck," London's Metropolitan Police said on Friday.
Glushkov was best known for being a close associate of the Russian oligarch and prominent Putin critic Boris Berezovsky, who was found dead on the bathroom floor of his ex-wife's house in Ascot, southeast England, in 2013.
Shortly after Berezovsky's death, Glushkov told The Guardian that he was also a target of the Russian government.
He alleged that both Berezovsky and Alexander Litvinenko, a former Russian spy who was fatally poisoned in 2006, had been on a Kremlin hit-list.
Glushkov said at the time: "I don't see anyone left on it apart from me."
On Wednesday, Glushkov's friend Alex Goldfarb also claimed that Russian intelligence agencies had held a grudge against Glushkov since the 1990s.
Glushkov was granted asylum in the UK in 2010. The Russian national previously worked at Berezovsky's car company LogoVaz and the Russian state airline Aeroflot, from which he was convicted of stealing $100 million last year.
He had been expected in commercial court on the morning of his death to defend a claim made against him by Aeroflot. An unidentified friend told The Guardian that Glushkov "had been getting ready for this for months."
British counterterrorism officers are leading the investigation "as a precaution" because of Glushkov's associations.
They added that there was "nothing to suggest any link" to the poisoning of the ex-spy Sergei Skripal in Salisbury that is the subject of a diplomatic dispute between Moscow and London.
FamousByVictory on March 16th, 2018 at 18:01 UTC »
Well honestly I'm expecting him to commit "suicide"
morrock14 on March 16th, 2018 at 17:42 UTC »
I think Putin has pretty well established that if you cross him, you are offed. He's a crime boss.
TooShiftyForYou on March 16th, 2018 at 17:37 UTC »
He told the Guardian he feared he was next to be killed after the deaths of Berezovsky, Alexander Litvinenko and Badri Patarkatsishvili.
Litvinenko died after being poisoned with Polonium-210 in London in 2006, while Georgian businessman Patarkatsishvili was killed in Leatherhead in 2008.
Glushkov said: "You have the deaths of Boris and Badri over a short period of time. Too many bodies are happening. I would say this is a little bit too much. I don't see anyone left on the list apart from me."
Putin is just brazenly having these guys murdered.