A Russian exile who was murdered in London was previously targeted by two mystery men from Moscow who brought him champagne.
Former Aeroflot deputy director Nikolai Glushkov, 68, was apparently strangled in his home in New Malden, southwest London, a week after the novichok poisonings of Sergei Skripal and his daughter Yulia.
Police are working on the theory that Mr Glushkov, like ex-Russian spy Mr Skripal and his daughter, was targeted by Russia’s spy agencies.
In mid-2013 Mr Glushkov accused the Kremlin of murdering his friend Boris Berezovsky, who was a critic of Russian president Vladimir Putin.
In November that year, he was found collapsed on the floor after sharing champagne with the two mystery men at Bristol’s Grand Hotel.
Keith Carr was the paramedic who treated Mr Glushkov that day.
Mr Carr, 71, said that emergency services had been called to a report that Mr Glushkov had collapsed on the floor the morning after drinking with the other men.
He told the Press Association: “He had carpet burns to his face and he was unsteady.”
Mr Carr said his patient had an abnormal heart rhythm, which was very fast.
“In 47 years as a paramedic I’ve never had anybody deliberately poisoned so it wasn’t foremost in my mind until he said: ‘I think they poisoned me’.
“I thought it was a bit far-fetched but when I saw the cardiac dysrhythmia I thought: ‘Something’s wrong, it’s not like any normal heart rhythm, so somebody’s got to him’.”
It is understood that detectives are struggling to find leads in the case of Mr Glushkov.
In August, the Met Police said they had obtained a total of 286 witness statements and seized 1,086 exhibits as part of their investigation.
A Scotland Yard spokesman said the Bristol incident in 2013 was a matter for Avon and Somerset Police, adding: “We are not prepared to discuss specific lines of inquiry in regards our investigation.”
Mr Glushkov claimed political asylum in the UK after Russia accused him and Mr Berezovsky of a criminal conspiracy related to Aeroflot.
UK authorities have identified two men alleged to have been behind the Skripal poisoning – Alexander Petrov and Ruslan Boshirov who are members of the GRU, Russia’s military intelligence service.
Russia has denied any involvement
The Skripals became critically ill after they were exposed to the military grade weapon, but have since been discharged from hospital.
Police have formally linked the attack on the Skripals to events in nearby Amesbury when Dawn Sturgess, 44, and her partner Charlie Rowley, 45, were exposed to the same nerve agent. Ms Sturgess died as a result.