As the investigation into the death of ex-Russian spy Alexander Litvinenko opens, evidence has been produced which points to three attempts on the former KGB officer’s life, the BBC reports.
Litvinenko, who died of radiation poisoning in 2010, said on his deathbed that the Kremlin were behind his attack.
Two men are wanted by the British to face murder charges, although Russia refuses to hand them over. There has been an international arrest warrant issued should they leave their home country.
Investigators are said to have followed a radioactive trail across London which suggested the previous two failed attempts to murder Mr Litvinenko.
The former Russian spy fled to the UK where he worked for MI6 and became a fierce critic of the Kremlin, including linking Vladimir Putin with a serious criminal.
His widow has said that the inquiry will give people “a chance to understand who killed my husband.”
Marina Litvinenko has been adamant since the passing of her husband that it was the fault of the Russians, with her lawyer describing his murder as “an act of state-sponsored nuclear terrorism on the streets of London.”
The British government are understood to have seen evidence which points to Andrei Lugovoi and Dmitri Kovtun’s involvement which stems from intercepted communications by the American security services.
A source close to the investigation said that while the evidence would be “inadmissible” in court, the British government were “confident that this was a state execution”.
It was previously ruled by a coroner that a public investigation would be preferable to an inquest, as this would allow some evidence to be held in private.
The judge led inquiry is chaired by Sir Robert Owen who was originally appointed as the coroner in the case. But he raised concerns at the time that there was sensitive evidence based on national security fears which would be better heard away from the press and public.
Mr Litvinenko died three weeks after becoming seriously ill in November 2006 following a meeting with two former Russian agents at the Millennium Hotel in Mayfair.
He had become a British citizen after his arrival in the UK and was considered a valuable source to the British security services, although some of his revelations including those relating to former Commission President Romano Prodi were not welcomed by the establishment.
Police investigating the murder say the isotope polonium-210 was put in Mr Litvinenko’s cup of tea and identified two suspects in the case, Lugovoi and Kovtun. The two Russians dispute the claim, as does the government.
Sir Robert says it will be “inevitable” that some of his final report will stay secret for security reasons.
But with poor relations already between Russia and the UK particularly with the situation in the Ukraine, diplomatic relations will inevitably remain frosty at least.