Who was the would-be killer arrested in London last month and what details are there of the boy who accompanied him?

The authorities will not disclose the identity of the suspect arrested and questioned over the alleged plot to murder Boris Berezovsky. He is understood to be a Russian national who was accompanied by a boy as cover.

The man checked into the Hilton in Park Lane after arriving at Heathrow on June 16. He was watched until his arrest on suspicion of conspiracy to murder on June 21.

Scotland Yard released the suspect into the custody of the immigration service on June 23. It is understood that it revoked the man’s visa on the ground that his presence in Britain was not conducive to the public good.

Was the decision to release him taken purely because of lack of evidence or was there political interference from above?

John Reid was still in charge at the Home Office and Tony Blair was in his final week as Prime Minister when the suspect was thrown out of Britain. It is inconceivable in the aftermath of the Litvinenko affair that they, and other senior ministers, would not have been informed about a possible plot to murder a second Russian dissident on British soil.

But police are adamant that there was no political meddling in the decision to release rather than charge the suspect. Police dropped the case without referring it to the Crown Prosecution Service, suggesting that the evidence was weak.

Knowledge of the operation was limited to a small circle of officers. Sir Ian Blair, the Metropolitan Police Commissioner, professed himself “extremely satisfied” yesterday with the way the inquiry was handled.

Why did it take almost a month for details to emerge?

The timing of the disclosure of the details of the alleged plot suggests that politcal hands may have been at work.Although Gordon Brown has decried spin, it clearly suited the Government to be able to point to another murder attempt, possibly sponsored by Moscow, in a week of tit-for-tat diplomatic expulsions. The story of the plot, which appeared first in The Sun on Wednesday, might also have been planted to strengthen Britain’s efforts to win greater international support for its stance against the Kremlin.

How many other Russian hitmen are there thought to be in Britain?

The idea that a second political killing may have been attempted so soon after the murder of Alexander Litvinenko has caused considerable alarm. While Britain wants to extradite Andrei Lugovoy for the murder of Mr Litvinenko, Russia has long been seeking the extradition of 21 people — including Mr Berezovsky and the Chechen leader Akhmed Zakayev — from London. If elements in Moscow, frustrated by progress on the legal front, are prepared to turn to killing, then that is an extremely worrying development. Mr Berezovsky has said he has been warned several times of plots to murder him, and Oleg Gordievsky, the Russian Cold War defector, said he was aware of such plans.

Is this distracting the work of Scotland Yard’s anti-terrorist officers and the intelligence services? Are there any assigned permanently to this case?

SO15, Counter-Terrorism Command, is fully engaged dealing with about 30 Islamist terrorist plots and preparing for dozens of pending terrorist trials. It is understood that no officers are currently engaged on the Berezovsky plot inquiry.

Who is calling the shots back in Moscow? Is this a rogue FSB operation or ordered from Putin?

Many in Russia believe that it is no coincidence that killings and plots have spiralled in the final year of Mr Putin’s presidency as a power struggle goes on between rival Kremlin factions over the succession. One theory has the siloviki — the military and FSB faction — conspiring to create a crisis with the West to force Mr Putin to change the Constitution and stay on for a third term. Another has the Kremlin’s liberal wing, fearful of a hardline successor to Mr Putin, inciting plots to provoke him into a backlash against the siloviki.

Mr Putin is losing the ability to control the infighting as the elections next March get nearer and his authority weakens. His most virulent critics insist, however, that the former KGB agent remains fully in control.

They point to a law passed by the Russian parliament last year that sanctions FSB killings of “terrorists” abroad. Mr Berezovsky’s call for a revolution to overthrow the Putin regime would have been enough to turn him into a target, they say.

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