02/05/2012 11:03 BST | Updated 02/05/2012 11:32 BST

Gareth Williams Inquest: 'Highly Likely' Third Party Involved In MI6 Spy's Death, Police Say

The death of MI6 spy Gareth Williams was "most suspicious" and it is "highly likely a third party was involved" in his demise a senior Met officer involved in the investigation has said.

Speaking outside the inquest into his death after a corner ruled it was most likely he was unlawfully killed, DCI Jackie Sebire, said she had "always been satisfied that a third party may have been involved in his death… The investigation will now refocus and actively pursue all the lines of inquiry".

Sebrie pleaded for anyone with information to come forward. "His naked body was found in the most suspicious of circumstances," she said.

Minutes before the family of Williams railed against the "total inadequacies" of the the original police investigation of his death.

In a statement read out by the family's solicitor Robyn Williams after his inquest closed, the family said their grief had been "compounded" by the failure of MI6 to report their son missing, and the specialist branch of the police SO15 for failing to hand over all the relevant information.

"To lose a son and a brother at any time is a tragedy. To lose a son and a brother in such circumstances that have been outlined in the course of this inquest only compounds the tragedy," the said in the statement.

"Gareth was and always will be a special and adorned son and brother. We miss him every single day and cannot describe the depth of sorrow his absence leaves in our lives."

The plea came after the coroner overseeing the inquest into the death of MI6 spy Gareth Williams has said that it is "unlikely" that his mysterious death will ever be solved but it was likely he was unlawfully killed.

In assessing the initial investigation into his death, Dr Wilcox discredited both the police and MI6 in how they handled the case.

MI6 had previously been accused of mishandling evidence and failing to hand over evidence to the inquiry, while police were accused of not properly investigating a bag of nine USB sticks handed over to them during the investigation.

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