MI6 bag spy Gareth Williams killed by 'secret service dark arts' On Friday, at a pre-inquest review, the hearing was told that his family believe Mr Williams was murdered by a member of "some agency specialising in the dark arts of the secret services." Concerns were also raised about how Mr Williams' MI6 employers failed to raise the alarm when he failed to show to work. The court heard this meant delays in finding his body resulted in the post mortem was "ineffective." Anthony O'Toole, representing the family, told the hearing that relatives believed Mr Williams was murdered by a member of "some agency specialising in the dark arts of the secret services." He said there was a "high probability" that a third party was in the flat. Police released two e-fits of a couple who said they were visiting Mr Williams's Alderney Street home "The unknown third party was a member of some agency that specialised in the dark arts of the secret services and perhaps evidence was removed from the scene post mortem by an expert in those dark arts," he said. He said the family had no view on whether it was a foreign agency or a British agency that was behind either the murder or the cover-up. The family still do not know what Mr Williams did for a living. Mr O'Toole said that the family had hoped that forensic evidence might help to convict the killer if the police found a suspect. But following the discovery that DNA found on his hand belonged instead to a police worker, there was now no forensic evidence, which could identify the killer. He said that Mr Williams, of Anglesey, North Wales, had attended two "operational development courses" in the moths before his death. "With effective from March 18, 2010, he could be operationally deployed," he said. In our submission, to properly explore the circumstances of the death, we do need to know something of the deceased's work. SIS (MI6) say the risk to the deceased was assessed to be low, but we don't know why ... we got a bland statement from SIS that the death is nothing to do with his work. The coroner, Dr Fiona Wilcox assured Mr O'Toole that "I absolutely intend to follow the evidence in this case." The hearing heard that his body could not have locked himself in the sports bag. But in another key blunder, DNA found on the spy's hand, thought to be crucial to the case, turned out to be from a forensic scientist who took evidence at the scene. Human error in the way DNA results was then fed into a computer, which led to false leads being pursued needlessly until this year. Forensic lab LGC is to blame for the blunder, the hearing heard. , said it throws into doubt the reliability of their work on this case, as well as others. She expressed frustration over delays as "an ongoing problem" as she called for inquiries into the DNA "error." Dr Wilcox told the hearing that whether Mr Williams was alive inside the bag and locked it himself "was at the very heart of this inquiry." The hearing was told that experts who worked on the case agreed that the code breaker could not have locked the bag himself from the inside. They could be asked to re-enact how he could have got into the bag by giving a live demonstration in court. Dr Wilcox told the court there was a lack of pathological evidence to prove Mr Williams made a "frantic attempt" to get out of the bag. Meanwhile, a "Mediterranean couple" who were reportedly seen visiting the flat has been ruled out as a red herring by police. Agents from both MI6 and GCHQ, where Mr Williams had been seconded from, are due to be called to give evidence when the inquest opens next month. Applications were being made by GCHQ lawyers for agents to be allowed to give evidence anonymously and behind a screen. Further "corporate statements" from both organisations are set to be tendered, which lawyers for MI6 told the court would "paint a picture and set the scene." Evidence will also be given about the contents of Mr Williams' locker at GCHQ in Cheltenham, Glos, which the hearing was told several people had access to. The inquest is unlikely to be shown composite video of material found on Mr Williams' iPhone that was recovered from his work locker. The inquest is due to start on April 23 and last five days, with 30 witnesses set to be called to give evidence. Witnesses will include Gareth Williams's sister and the police officers who opened the front door and discovered the padlocked bag containing the body. Organisers of the ladies fashion course Mr Williams' is said to have secretly enrolled on will give statements to the inquest. Three colleagues, known as witnesses K, F and G, will be called to give evidence and will take questions from his family, the court heard. Witness K will give evidence about Williams' "state of mind on his last trip" before his death. An officer from Scotland Yard's counter terrorism command will also attend the inquest to explain its official role following a request from the spy's family, Witness K, a colleague at GCHQ, will give evidence about Mr Williams' "state of mind on his last trip" before his death. Witness F was considering taking over the MI6-owned flat when the spy returned to Gloucestershire. Meanwhile Witness G, Mr Williams" line manager, will be forced to explain why the alarm was not raised sooner when Mr Williams failed to show to work. The alarm was raised about by a GCHQ HR manager when she rang the Metropolitan Police, who went to his house for a routine "welfare check." Dr Wilcox told the hearing that he wanted the inquest to go ahead for the sake of Mr Williams" family.