Up to 40 spies could give evidence anonymously at the inquest into the mysterious death of MI6 agent Gareth Williams, a coroner was told today.
Paul Knapman adjourned an inquiry into the 31-year-old's death as Scotland Yard detectives wait for the results of a fresh round of forensic tests.
Counter-terrorism officers have interviewed "in the region of 40" of the expert codebreaker's colleagues at MI6 and GCHQ, Westminster Coroner's Court heard.
They have been passing on their findings to a team of investigators from the force's Homicide and Serious Crime Command who are responsible for the inquiry.
The inquest heard that some or all of them could give evidence about Mr Williams, whose naked and decomposing body was found in a bag in the bath of his Pimlico flat last August.
Detective Chief Inspector Jackie Sebire admitted the likelihood of tracing a Mediterranean couple seen at Mr Williams's home weeks before his death is diminishing.
She said it is "very unusual" for two teams of officers to be working on a suspicious death inquiry, but said the victim's secretive occupation was the reason.
Speaking about forensic tests, she added: "We have done a phased submission of tests to the laboratory. We are still waiting for some outstanding tests that went out before Christmas."
After a 10-minute hearing, Dr Knapman adjourned the inquest until Thursday March 31, but said it is not known whether it will go ahead then.
Dr Knapman said he had read a report summarising the forensic tests written by a police expert but added "it is a matter of some regret" that the inquest cannot go ahead.
He said the Mediterranean couple have not come forward, there are no new clues and it appears to be "less and less likely that something will happen".
The coroner added: "The fact you must face is that in six months or so they have not come forward, this couple, have they?"
Mrs Sebire replied: "That is correct, sir."
The senior detective added that a "raft" of forensic tests have taken place and she is still waiting for the results of some submitted six months ago and more recently.
Mrs Sebire said her team is dealing with the dead man's private life, forensic tests and other inquiries while counter-terrorism officers are responsible for liaising with spy agencies.
She said she has regular meetings with her counterpart, passes instructions to him on who should be interviewed and could arrange to see a potential witness if necessary.
Dr Knapman said Mr Williams' family expect a "thorough inquest" and was told they have "no problem whatsoever" with his colleagues being granted anonymity.
The pre-inquest hearing was told they were invited to attend today but did not come. They have appointed a solicitor to represent them.
Mr Williams, of Anglesey, North Wales, was found in a large North Face holdall, sealed by a padlock, at his top-floor flat in Alderney Street on August 23.
The mysterious discovery sparked a painstaking Scotland Yard investigation, worldwide media frenzy, and several outlandish conspiracy theories.
A battery of post-mortem tests have so far failed to determine how he died and police found it would have been impossible for him to have locked himself inside.
No evidence of drugs, alcohol or poisons have been found but police said anyone zipped inside the bag would have quickly found the temperature unbearable and suffocated within 30 minutes.
Investigators believe the fitness and fashion enthusiast probably died accidentally at the hands of a mystery bondage sex partner he may have met on London's gay scene.
They found he enjoyed going to drag cabaret shows, had £15,000-worth of unworn women's designer clothing in a wardrobe, and had visited bondage websites.
Police have released e-fit images of a young, casually-dressed Mediterranean couple who a neighbour buzzed through the communal doors of Mr Williams's block in June or July.
Mr Williams was a mathematics prodigy who worked as a cipher and codes expert for GCHQ, the Government listening station, but had been on secondment to MI6.Reuse content