News In Depth
More questions for spy's family
Family members will walk away from the inquest into Gareth Williams's death with more questions than answers.
Scotland Yard has vowed to pursue all new evidence which emerged over the past week and a half.
Jackie Sebire, the senior detective on the case, said fresh attention could be shone on the codebreaker's colleagues at MI6.
But a source close to the inquiry said officers are still "some way off a breakthrough".
Here is how the inquest has tried but failed to solve the 21-month riddle of Mr Williams's death:
Q: Were secret agents specialising in the "dark arts" responsible for Mr Williams's death in his Pimlico home?
A: Detectives have said from the start that third-party involvement was likely.
But little suspicion outside his family was raised on the activities of MI6 until questions emerged on Tuesday about nine computer memory sticks and a bag withheld from the inquiry.
Detective Superintendent Michael Broster said: "I have seen no information or evidence that someone is involved. I am not saying that a member of SIS is not involved. I don't know."
Q: Is it possible that he was able to get inside a North Face holdall in his bathtub before padlocking himself in?
A: Bag expert Peter Faulding said even world-famous escapologist Harry Houdini would have struggled to squeeze himself in.
Mr Faulding tried and failed to carry out the task more than 300 times before saying they were "unbelievable scenarios".
But William MacKay, who made more than 100 attempts with a yoga-practising assistant, said: "I would not like to say that it could not be done."
Q: Could a third party have been present when he died despite no trace of DNA or fingerprints?
A: Forensic experts said it was entirely possible that someone could break in and kill Mr Williams without leaving any evidence.
Ms Sebire says she remains convinced someone was there due to the suspicious circumstances.
Forensic expert Ros Hammond said there were hopes of a breakthrough "within a matter of weeks" from DNA tests on a green towel discovered in his kitchen.
Q: Why was there no sign of a struggle on his body? Could he have been drugged despite the lack of any poisons in blood tests?
A: Poisoning and asphyxiation are the "foremost contenders" in causing Mr Williams' death, pathologists said.
But experts believe there would have been signs of damage to his fingers and hands if he had struggled to get out of the bag within the three minutes it would have taken to suffocate.
The fact that Mr Williams was dead for up to 10 days before his post-mortem examination meant many poisons and/or bruise marks could have disappeared from his system during decomposition.
Q: Why did it take colleagues at MI6 more than a week to realise he was missing?
A: MI6 offered a range of excuses including his recent return from a trip to Las Vegas, delays on the trains and his imminent return to GCHQ.
Colleagues apologised to the family for the potential damage the mistake did to the police inquiry.
Referring to his failure to turn up to a meeting with his boss at 3pm, Coroner Dr Fiona Wilcox said: "I am really struggling to understand why you took no action at this point."
Q: Has information been withheld because shedding light on Mr Williams's work could jeopardise secret security operations?
A: Family lawyer Anthony O'Toole was blocked on several occasions from asking detectives and MI6 about the use of an apparently unvetted estate agent to let Mr Williams's flat in Pimlico.
Relatives suspect the decision may have compromised the safety of the property.
In addition, more than 10 employees linked to GCHQ and MI6 were allowed to give evidence behind a screen to protect their identities.
Q: Could Mr Williams's private life have had any significance in his death?
A: He had shown an interest in escapology and self-bondage.
He once tied himself to his bed and had to be cut free by his landlord and landlady in his rented flat in Cheltenham.
But Detective Constable Simon Warren said his interest in bondage footage on his computer was "an isolated (incident) among a sea of other data".