MI6 spy death inquest: 'No drugs or poison found' in body
MI6 officer Gareth Williams was probably not drugged, drunk or poisoned when he died, a toxicologist has told the inquest into his death.
But Denise Stanworth said she could not rule this out because of the time which had elapsed between his death and the post-mortem examination.
Mr Williams' body was found locked in a holdall at his London flat on 23 August 2010 - a week after his death.
His boss at GCHQ in Cheltenham earlier hailed him as "something of a prodigy".
Giving evidence, forensic scientist Ms Stanworth said some anaesthetics, solvents and the substance amyl nitrate may not have been detectable, because his body was left for so long.
It took a week for MI6 to investigate Mr Williams' disappearance, meaning the post-mortem exam was carried out nine days after he died.
A small amount of alcohol, and traces of the sedative GHB were found, but both were likely to have been produced by his body as it decomposed after death.
An extensive search for "old-fashioned poison" came back negative, although Ms Stanworth said volatile agents could not be ruled out.
Mr Williams' former boss at government listening agency GCHQ earlier described him as a "world-class" intelligence officer.
Stephen Gale said Mr Williams had joined GCHQ aged 21 with a first class degree in mathematics and PhD in computer sciences. "It was quite remarkable that he had achieved those levels of qualifications at such a young age," he said.
The agency paid for him to gain further qualifications in advanced mathematics at Cambridge University.
Mr Gale said: "Colleagues recall a young man who was very close to his father - he spoke about their climbing trips together.
"They remember him as a keen cyclist. One colleague said it was like a red bullet flying around the place."
Mr Williams was on a three-year secondment with MI6 in London but wanted to return to his role at GCHQ.
On Thursday morning, an MI6 officer denied the secret service was involved in a cover-up over the codebreaker's death.
The officer - Witness F - gave evidence anonymously from behind a screen.
She apologised to Mr Williams' family on behalf of MI6, saying they were "profoundly sorry" for the delay in reporting the spy missing.
Witness F admitted that HR policy was not followed and that it "clearly took too long" to notice the codebreaker's absence from work.
She blamed Mr Williams' line manager - Witness G - for a "breakdown in communication", but said he should not face disciplinary action.
Mr Williams' relatives walked out of the inquest in tears during Witness F's evidence, and their lawyer Anthony O'Toole said the agency had shown a "total disregard for Gareth's whereabouts and safety".
Mr O'Toole blamed the delay for preventing the family from saying goodbye to Mr Williams while his body was in an "acceptable form", and for making it more or less impossible for detectives to establish how he died.
During her evidence, Witness F denied that officers from the secret service entered Mr Williams' flat, before or after the discovery of his body.
She said that MI6 had not tampered with any electronic evidence on Mr Williams' computer, and denied the secret service had leaked information to the media that the codebreaker visited bondage and sadomasochistic websites.
Mr O'Toole asked Witness F whether speculation about Mr Williams' private life might have made him unsuitable for intelligence agency work.
She indicated his sexual preferences would not, in themselves, pose a problem: "There's no set template as to what [an employee's] lifestyle should be. Individuals have lifestyles and sexual choices which are perfectly legitimate.
"Our concern in the vetting process is to identify whether anything in the individual's background, lifestyle, creates a risk for him."
An internal secret intelligence services' review in 2011 found no link between the codebreaker's death and his work.