MI6 warned it is not above the law

Britain's top police officer has warned MI6 that it is not above the law as they continue to investigate the death of Gareth Williams. Inquiries have yet to yield a culprit, with forensic experts still hoping for a breakthrough from DNA tests on a green towel discovered in his kitchen.

Last week it was announcement that around 50 of Gareth's colleagues will take part in DNA screening after coroner Dr Fiona Wilcox said the 31-year-old was probably killed and it "remained a legitimate line of inquiry" that the secret services may have been involved in the death. However, a narrative verdict was recorded at the inquest into the spy's death.

Bernard Hogan-Howe, Scotland Yard's Commissioner said an independent forensics review will form a central part of fresh efforts to solve the 21-month inquiry into how the codebreaker's body ended up in a holdall. Detectives have also been told to deal directly with the intelligence agency in a break with tradition at the Metropolitan Police.

But Mr Hogan-Howe was angered by the "unacceptable" breakdown in communication which saw evidence fail to come to the senior investigating officer until last week at an inquest. When asked what powers he had to ensure MI6 co-operated, he told reporters: "It's the law." He said mass screening in the case would be carried out on a "voluntary" basis.

Mr Hogan-Howe said: "Of course it may well be that Gareth Williams' death has nothing to do with employment. All we need to do is to make sure that all areas of his life were fully explored."

Mr Williams, a fitness enthusiast originally from Anglesey, North Wales, was found in the bag in his flat in Pimlico, central London.