The MI6 overseas spy agency found nine computer memory sticks at Gareth Williams' workplace but did not hand them over to detectives until this week, said Detective Chief Inspector Jackie Sebire, who is leading an inquest into the death.
Williams, 31, worked for Britain's secret eavesdropping service GCHQ. He was attached to the MI6 overseas spy agency when his remains were found in August 2010 at his London apartment inside the bag, and placed in a bathtub.
Sebire told a London inquest hearing that she did not become aware of the memory sticks found by MI6 officers in Williams' office until Monday. She said she also did not know about a black gym bag—similar to the one Williams' body was found in—that officers discovered at the workplace.
"I would have expected to have been told," she told Westminster Coroner's Court. "What I knew was that Gareth's email accounts had been checked but I did not know that other media had been checked."
Coroner Fiona Wilcox criticized British agents for the failure to pass on the evidence.
"I suggest that this means you have not been completely impartial in this case," she told Michael Broster, a counter-terrorism officer who was called to give evidence about the search of Williams' office.
Detectives were ordered to re-examine the black gym bag in the courtroom Wednesday, the last day of the inquest.
Investigators have been baffled by how exactly Williams died and have so far made no arrests, although a senior detective has told the inquest she believes that at least one other person must have been involved.
Williams' relatives maintain that his death had to do with his highly secret work. Police have suggested it may have been due to a sexual encounter gone awry.