30/04/2012 07:59 BST | Updated 30/04/2012 11:32 BST

Gareth Williams Death: MI6 Spy Likely Poisoned Or Asphyxiated, Pathologists Believe

Poisoning and asphyxiation are the "foremost contenders" in the sports bag death riddle of MI6 spy Gareth Williams, an inquest heard today.

Mr Williams was probably suffocated or killed by a poison which disappeared in his system during decomposition, pathologist Benjamin Swift said.

Dr Swift said his post-mortem examination was hampered by levels of heat within the bag after radiators were mysteriously turned on in Mr Williams's top floor flat in the middle of summer.

Examinations two days after Mr Williams was found in a holdall in his bathroom gave cause of death as "unascertained".

But under questioning at Westminster Coroner's Court, Dr Swift said poisoning or asphyxiation such as suffocation were "probably rather than possibly" to blame.

Dr Swift said the two causes of death "were certainly two of the more prominent" beliefs as he conducted examinations.

When family lawyer Anthony O'Toole asked if there were any other possible causes of death, Dr Swift replied: "I would never say never but those are the foremost contenders."

There were no injuries indicating Mr Williams had struggled to get out of the bag, in which he was found naked and in the foetal position, the pathologist added.

But no tablet deposits were found in his system and there was no bruising consistent with strangulation.

Dr Swift said he believed Mr Williams would have died shortly after his last known movements on August 15.