A British spy whose naked and decomposing body was found in a locked bag in his apartment likely died through poisoning or suffocation, a pathologist who examined the body told his inquest.
Either poison or asphyxiation was "probably rather than possibly" the cause of death, pathologist Benjamin Swift told the inquest into the death of Gareth Williams, 31, a codebreaker working for external intelligence agency MI6.
Williams' family have said they believe secret agents versed in the "dark arts" tried to cover up his death.
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No traces of poison have been found in Williams' body, which was discovered in August 2010 -- a week after he failed to arrive at work -- in his flat in Pimlico, central London.
But post-mortem examinations were hampered by the effects of heat within the padlocked holdall, after radiators were turned on in the apartment despite the summer warmth, Swift said. No official cause of death has been registered.
Experts who carried out experiments with a similar bag told the inquest last week it would have been extremely difficult for Williams to lock himself in the holdall alone, after speculation he might have done so as part of a sex game.
But a second pathologist told the inquest on Monday that it was "more likely (Williams) was alive when he entered the bag than that he was dead".
Richard Shepherd, who carried out a third post-mortem on the body, said: "I think it would have been a very difficult process to achieve, getting a (dead) body so neatly into a bag."
But there were no signs of Williams having tried to escape.
"Were he to be alive and struggling I would anticipate there to have been injuries," Shepherd said.
A third pathologist said the carbon dioxide buildup inside the bag would have been a plausible cause of death, resulting in headaches and confusion, a soporific state, and eventually unconsciousness and cardiac arrest.
The inquest heard last week that Williams' previous landlady once found him tied to a bed, while records on his home computer showed he had visited websites about claustrophilia -- the love of enclosure -- and bondage and sadomasochism.
High-end women's clothing and shoes worth some £20,000 ($32,400, 24,500 euros) were also found in the spy's immaculate flat.
