British spy Gareth Williams was “dead or unconscious” and was almost certainly placed in a sports bag by another person, an inquiry into his death in London was told Friday, it is reported.

Expert Peter Faulding tried to re-create the code-breaker’s bizarre death by trying to climb into a bag inside a bathtub and lock it himself 300 times. He failed every time, according to a report of the day’s inquest evidence in the Daily Telegraph.

Faulding said the task would have eluded even escapologist Harry Houdini.

UK intelligence officer: No cover-up in 'spy in the bag' case

He said he believed a third party was present, describing theories that Williams got inside the bag unaided as "unbelievable."

Video footage of Faulding attempting to re-create the death was shown to the inquest.

Police discovered the naked decomposing body of the 31-year-old spy padlocked inside a red sports bag in the bathtub of his flat in London in August 2010.

The strange circumstances surrounding Williams’ death have prompted a number of theories, and police eventually concluded he had been playing an auto-erotic sex game that went badly wrong.

Earlier this week, the inquest heard from Williams’ former landlady, who once found the spy in bed with his hands tied to the headboard wearing nothing except boxer shorts.

Faulding, a former Parachute Regiment reservist who specializes in rescuing people from confined spaces, was unable to lock himself inside an identical bag in the bath, according to a Press Association report.

"I couldn't say it's impossible, but I think even Houdini would have struggled with this one," he said, according to the PA. The expert added: "My conclusion is that Mr. Williams was either placed in the bag unconscious, or he was dead before he was in the bag."

He also raised the idea the bag was deliberately placed in the bath so “bodily fluids” could drain away.

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Andrew Winning / Reuters

Ian and Ellen Williams and Cerri Subbe, the mother, father and sister of British MI6 agent Gareth Williams, leave Westminster Coroner's Court, in central London April 23, 2012.

Criminal charges over the death of a British spy – whose body was found in a sports bag – are a “real possibility,” a lawyer for police reportedly told a coroner Monday.

Gareth Williams, 31, a math prodigy who graduated from university at the age of 17, was found dead in his immaculate apartment in Pimlico, London, in August 2010.

At the opening of a hearing into the cause of his death, Vincent Williams, a lawyer for London’s Metropolitan Police, said he sought to block the coroner from making video footage related to the case public, The Guardian newspaper reported.

The lawyer said a "careful line must be struck between open justice" at the hearing and the investigation by police, according to The Guardian.

Asked why information should not be made public, the lawyer told the coroner “because there is a live, complex, ongoing investigation taking place.”

Spy death inquiry looks at bondage link

"It is because there may be criminal proceedings further down the line that the commissioner feels that the pattern of disclosure … has to be done with some care,” the lawyer added, saying charges were still a "real possibility."

Coroner Fiona Wilcox said there was a risk of harm to the U.K.’s national security and relations with other countries if some of those giving evidence at the hearing were named, The Guardian reported.

Mystery couple sought in UK cyberspy's bizarre death

Williams’ relatives have expressed fears that "some agency specializing in the dark arts" will prevent them from finding out the truth about his death, The Guardian said.

The dead man’s sister, Ceri Subbe, told the hearing she did not enjoy the culture of “flash car competitions,” “post-work drinking” and “rat race” at MI6, the U.K.’s secret intelligence service, The Telegraph newspaper reported.

Wilcox asked Subbe if she was surprised that more than £20,000 worth of female clothing was found in Williams’ apartment.

“I am not surprised, he was very generous with gifts,” Subbe said, adding that he may have collected the clothes because of his interest in fashion.

She said Williams was a cautious man and would not have let anyone inside his home if they had not been security vetted.

The hearing at Westminster Coroner’s Court in London is continuing.

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