British police say no sign of forced entry has been found at the home where a London-based Russian businessman died from a neck compression.

Metropolitan Police Commander Clarke Jarrett said Monday the forensic investigation into the death of businessman Nikolai Glushkov is continuing in the New Malden neighborhood where he lived.

Glushkov, 68, was found dead at his southwest London home on March 12. He was an associate of Boris Berezovsky, a wealthy Kremlin critic who died under disputed circumstances in 2013.

The murder investigation is being headed by counterterrorism detectives because of the "associations Mr. Glushkov is believed to have had," police said.

Glushkov had worked for various Berezovsky enterprises including the car factory AvtoVAZ and flagship Russian airline Aeroflot.

He was arrested in 1999 and put on trial for embezzling $7 million from Aeroflot. In 2004, he was sentenced to three years and three months in prison, but released because of time served.

Last year, Glushkov appeared on a list published by the Russian Embassy in London of Russian citizens wanted for serious crimes whom the U.K. had refused to extradite. It said Russia had sought his extradition in 2015 "for committing a number of severe financial offences on the territory of Russia," but the British government refused.

Police have said they do not see a link between the Glushkov case and the recent poisoning of ex-spy Sergei Skripal and his daughter Yulia in the English city of Salisbury.

British police have contacted other Russian exiles in the last few days to discuss their safety in light of the recent attacks.