Police have refused to comment on a report that a spy found dead in a holdall could not have died alone.
Gareth Williams, 31, was on secondment at the Secret Intelligence Service, MI6, from GCHQ in Cheltenham, when he was found dead last month.
His naked body was discovered in a padlocked North Face holdall placed in the bath of his flat in Pimlico, London. Mystery surrounds his death and police continue to investigate. They regard the case as "suspicious and unexplained".
The Daily Mail said police were certain he was padlocked into the large holdall by someone else. It said he was alive when he got into, or was forced into, the bag, and died from suffocation.
There have previously also been reports elsewhere that Mr Williams died alone.
Scotland Yard declined to comment on the new claim, or a suggestion in the same story that the outer door of Mr Williams' Government flat in Pimlico, central London, had been locked from the outside.
The Yard has previously announced that it wants to identify a man and woman, both of Mediterranean appearance and aged between 20 and 30, who were let into the communal entrance of his flat late one evening in June or July. The Mail reported that they are understood to have had a set of keys to the flat, though again the Yard had no comment.
The report comes a day after Mr Williams' funeral in North Wales.
The head of MI6, Sir John Sawers, made the journey from London to the small Bethel Methodist Chapel in Anglesey to support Mr Williams' family and represent the maths genius's colleagues who could not attend. Outside church, when asked if the investigation would ever get to the bottom of what happened to Mr Williams, Sir John said it was not for him to say.
He insisted it was a police matter and said: "It has been a desperately sad period for the family since Gareth died. It has been very difficult for them and I wanted to be here today as the only public face of the Secret Intelligence Service. My deepest sympathies go to the family."