Evidence against at least two men suspected of being involved in a plot to murder the Russian agent, Alexander Litvinenko, is due to be sent to crown prosecutors in the next week.
Detectives believe that the former spy was poisoned on two different occasions after his assassins decided they had not used enough of the radioactive material polonium-210 to kill him the first time.
The police file provides evidence against two Russian businessmen, Andrei Lugovoi and Dmitri Kovtun, both former KGB officers. The two men are in Russia and have denied being involved in the murder plot.
Mr Litvinenko became ill on the night of 1 November and died on 23 November.
Scotland Yard officers who travelled to Moscow were allowed only limited access to Mr Kovtun and Mr Lugovoi. Because of this, and the Russian authorities' refusal to extradite the suspects to Britain, it looks almost certain that the Crown Prosecution Service will not bring any charges.Reuse content