Counter-terror police are leading an investigation into the "unexplained" death of a man in London.
He is believed to be Russian businessman Nikolai Glushkov, who claimed political asylum in the UK after being convicted of fraud.
The Metropolitan Police said its specialist unit was looking into it "as a precaution because of associations that the man is believed to have had".
There was no evidence linking the death to the incidents in Salisbury, it said.
In a statement, it said the man in his 60s had been found at a residential address in New Malden on Monday night.
The man has been identified, but not formally. However, next of kin have been informed.
Mr Glushkov, 69, is the former deputy director of Russian state airline Aeroflot.
He was jailed in 1999 for five years after being charged with money laundering and fraud.
After being given a suspended sentence for another count of fraud in 2006, he fled to the UK to seek political asylum and became a critic of Russian President Vladimir Putin.
Mr Glushkov also had a close friendship with fellow Russian businessman Boris Berezovsky, who came to the UK in 1999 after falling out with Mr Putin.
Mr Berezovsky was found hanged in the bathroom of his Berkshire home in 2013 and an inquest recorded an open verdict.