Police investigating the murder of a Russian businessman exiled in London have today released CCTV footage of a black van seen driving past his home on the night he was strangled.

Scotland Yard say they need to find the driver of the Volkswagen Transporter filmed near Nikolay Glushkov's suburban house the night before he was found dead earlier this year.

The 68-year-old, who was a close friend of Vladimir Putin critic Boris Berezovsky, died at his house on Clarence Avenue, New Malden, on March 12.

He was found dead by his daughter, Natalia, just eight days after the nerve agent attack on spy Sergei Skripal in Salisbury in March.

Police waited four days to launch a murder investigation as sources said his death was made to look like he had hanged himself.

Mr Glushkov was one of the last surviving members of an ill-fated circle of Russian exiles - led by Putin's enemy Boris Berezovsky - who was also found dead five years ago.

The black van police wish to trace in connection with the murder of Russian businessman Nikolay Glushkov

Nikolai Glushkov, 68, was found dead by his daughter, Natalia, right, at his suburban home in New Malden just eight days after the nerve agent attack on spy Sergei Skripal in March

An inquest opening heard his cause of death was compression to the neck, believed to be by strangulation.

A spokesman for the Metropolitan Police said: 'The Volkswagen van was seen in and around Clarence Avenue between 7.30pm and 10.30pm on Sunday March 11.

Mr Glushkov, an outspoken critic of Putin, was strangled but police were initially unsure if it was suicide

'Detectives are keen to identify the van and driver, who they believe could have information that may help with their inquiries.'

Mr Glushkov fled Russia after being accused of fraud during his time as deputy director of the Russian airline Aeroflot, and had lived in London for two years.

Last year, during a trial in absentia he was sentenced to eight years in a Russian prison, convicted of stealing £87 million from the airline.

He was due to attend the commercial court in London to defend himself on March 12 – the day his body was discovered.

Police, who launched a murder investigation four days after his death, say they have obtained a total of 286 witness statements and have seized 1,086 exhibits to date.

There is currently nothing to suggest any link to the attempted murders in Salisbury, or any evidence that he was poisoned, the force added. No arrests have been made.

Mr Glushkov was jailed in Russia in 2000 and held at the notorious Lefortovo Prison for five years until being cleared of fraud and money laundering and freed.

Mr Glushkov claimed political asylum in Britain and decided to live a quieter life in suburban south London before he was found dead

Mr Glushkov had lived in this suburban London home for two years before his murder on the eve of a High Court case

Police hunting for clues inspected the extension and lifted the patio as the mystery over his death continued

Glushkov's Land Rover was also taken away by detectives, who insist his death has nothing to do with the Skripal assassination attempt

However, at the time of his death he was preparing for a £90million High Court showdown with his former employer Aeroflot.

Mr Glushkov was being sued by the airline, which is 51 per cent state-owned, for the return of £90million which it alleges he embezzled along with Boris Berezovsky, the anti-Putin oligarch who is thought to have committed suicide in 2013.

Mr Glushkov was handed a second eight-year sentence by a Russian court in his absence over the alleged theft from Aeroflot, where he was previously finance director.

Mr Glushkov's former bodyguard revealed the extent of his worries over his safety and the measures they took to preserve his safety.

The minder told how Mr Glushkov had hatched an escape plan which included a hideaway should his life be put in danger.

He said: 'When we were informed things were a little tense, we were told to prepare a getaway for Glushkov.'

The bodyguard had also worked with Glushkov's friend and former business partner Boris Berezovsky and said the exiles saw poison as 'always a threat'.

The security guard said: 'Boris [Berezovsky] spoke openly that the orders came directly from Putin to eliminate him and his friends.'

Boris Berezovsky was said to have taken his own life after he was found strangled at his Surrey mansion in 2013, although Mr Glushkov was always among those who refused to accept that his billionaire oligarch friend killed himself.

Another of his close acquaintances, Georgian billionaire Badri Patarkatsishvili, 52, also died in mysterious circumstances five years earlier.

In that case, police investigated claims he was the target of an assassination plot but a coroner was told he probably suffered a heart attack.

Mr Glushkov's friend Boris Berezovsky was found dead in his Berkshire home in 2013 and the death of another of their circle, Badri Patarkatsishvili, is also unexplained

Glushkov said shortly after close friend Berezovsky's death in 2013: 'You have the deaths of Boris and Badri over a short period of time.

'Too many bodies are happening. I'd say this is a little bit too much. I don't see anyone left apart from me.'

The Home Secretary has already ordered a fresh official inquiry into a number of other deaths in Britain that could be connected to Russia.

Anyone with information that could assist the investigation should call police on 0800 789 321.