Scotland Yard has launched a murder investigation after a man who is reported to have worked for the British intelligence services was found dead.
The man has been named locally as Gareth Williams, believed to be in his 30s.
His body was found on Monday afternoon stuffed in a large sports holdall in the bath in the top-floor flat of a building in Pimlico, within walking distance of the MI6 headquarters in central London.
Detectives investigating the murder believe he could have been killed up to two weeks ago.
It is also claimed the victim's mobile phone and a number of SIM cards were carefully laid out elsewhere in the flat.
According to the Press Association, the man was employed as a communications officer at the GCHQ 'listening post' in Cheltenham, Gloucestershire.
But he is believed to have been on secondment to the riverside headquarters at MI6 about half a mile from the flat.
Officers had visited the flat in Westminster after reports that he had not been seen for some time.
A Home Office pathologist failed to find a cause of death following a post-mortem examination of Mr Williams' body.
Further tests, including toxicological analysis of his blood for evidence of drugs and alcohol, will now take place.