The Crown Prosecution Service (CPS) has advised the MPS of its decision to seek the extradition of Andrey Lugovoy from Russia to the United Kingdom for the murder of Alexander Litvinenko

17 November 2006

Mr Litvinenko’s condition worsens and he is transferred to University College Hospital under police guard.

20 November 2006

Deputy Assistant Commissioner Peter Clarke, head of the Metropolitan Police’s counter terrorist unit, begins investigating the case as a suspected poisoning.

23 November 2006

Mr Litvinenko dies. The police state they are now investigating “an unexplained death”.

24 November 2006

Police find radioactive traces are found in Itsu sushi bar.

Cobra, the high level committee of Ministers and the Security services meets to discuss the investigation.

25 November 2006

Police test people who may have been in contact with Mr Litvinenko or the sushi bar for poisoning.

Police search the sushi bar and a bedroom at the Millennium Hotel.

27 November 2006

Polonium-210 is discovered in offices at Grosvenor Street and Down Street.

Cobra meets for the second time.

28 November 2006

It is reported that police will also interview Mr Scaramella as a potential witness in the inquiry into the death.

Police are checking a further two addresses - the Sheraton Park Lane hotel and 58 Grosvenor St for traces of polonium-210.

29 November 2006

Two British Airways 767s are grounded at Heathrow and a third in Moscow after traces of radioactivity are found.

30 November 2006

Home Secretary John Reid announces that traces of radioactivity had been discovered in 12 locations, as well as the British Airways planes.

John Reid tells MPs that two Russian aircraft, one of which is currently at Heathrow, are also to be investigated.

An inquest into the death of Mr Litvinenko is opened and adjourned.

1 December 2006

The Financial Times quotes British officials as saying it was now a "strong probability" that the government would try to pave the way for a police team to go to Moscow by invoking a mutual legal assistance agreement recently reached by UK and Russian prosecutors.

Cobra meets for the third time.

4 December 2006

British police officers travel to Moscow to investigate Mr Litvinenko's death.

Further tests are carried out in central London.

5 December 2006

Mr Chaika, the Russian Prosecutor General, tells the press he will not extradite Russian citizens to Britain even if they are suspects. He says that any trial must take place in Russia.

6 December 2006

The British Police upgrade the case to a murder investigation.

7 December 2006

Russian Police announces that they opened a parallel investigation. They are investigating the attempted murder of Dmitry Kovtun, an acquaintance of Mr Lugovoi and Mr Litvinenko, during their meeting at the Millennium Hotel on 1 November.

10 December 2006

Metropolitan Police confirms that two officers have tested positive for traces of Polonium-219.

British police are briefed by colleagues in Hamburg.

British and Russian authorities interview Andrei Lugovoi in a Moscow hospital.

12 December 2006

Interpol becomes involved at the request of the British Police.

16 January 2007

British police ask for a second visit to Moscow. The Russians respond that this would be possible, after Russian officers have visited Britain.

31 January 2007

Scotland Yard hands a file on the investigation into the death of Mr Litvinenko to the Crown Prosecution Service.