British scientists say two more people have been contaminated with polonium 210

Dec. 1 - Pathologists carry out a post-mortem examination on Litvinenko's body.

- British scientists say two more people have been contaminated with polonium 210. Scaramella is admitted to hospital in London after the isotope was detected in his body. Traces of polonium 210 are also found in the urine of Litvinenko's widow Marina. Scaramella leaves hospital on December 6.

Dec. 4 - British police fly to Moscow as part of investigation.

Dec. 6 - British police say they are now treating Litvinenko's death as murder.

- British police and investigators from Russian Prosecutor-General Yuri Chaika's office question Kovtun in the same hospital where Lugovoy is being treated, apparently for radiation poisoning.

Dec. 7 - Litvinenko is buried in London's Highgate cemetery.

- Russian prosecutors launch their own murder investigation into the Litvinenko death. Prosecutors also open a criminal case into what they said was the attempted murder of Kovtun.

Jan. 9, 2007 - Russia announces that Lugovoy was discharged from a Moscow hospital at the end of December. Lugovoy declined to say whether he had been contaminated with polonium 210.

Jan. 31 - Scotland Yard police hand their file on the Litvinenko investigation to the Crown Prosecution Service.