The High Court has dismissed Jeremy Bamber's bid for the release of evidence which he claims could lead to his convictions for the murders of five family members more than 30 years ago being overturned.
The 59-year-old is serving life behind bars after being found guilty of murdering his adoptive parents Nevill and June, both 61, his sister Sheila Caffell, 26, and her six-year-old twins Daniel and Nicholas at White House Farm, Essex, in August 1985.
He has always protested his innocence and claims Ms Caffell, who suffered from schizophrenia, shot her family before turning the gun on herself.
The prosecution case at Bamber's trial in 1986 was that Ms Caffell could not have reached the trigger to kill herself if the silencer was attached to the murder weapon.
Jeremy Bamber, 59, is serving life behind bars after being found guilty of murdering his adoptive parents Nevill and June, his sister Sheila Caffell, 26, and her six-year-old twins Daniel and Nicholas at White House Farm
But Bamber's lawyers claim the Crown Prosecution Service (CPS) has not disclosed material about a second silencer which is said to have been found at White House Farm, which they argue is relevant to his latest attempt to overturn his conviction.
Joe Stone QC, representing Bamber, told a remote High Court hearing last week that 'it now seems almost certain that there is a second sound moderator' - evidence he suggested could 'significantly undermine the prosecution case'.
The court also heard that Carol Ann Lee - author of a book on which a recent ITV drama about the killings, White House Farm, was based - had been given 'a number of sensitive case documents' by the original investigating officer, former detective superintendent Michael Ainslee, who is said to have later destroyed the items at his home.
Mr Stone argued his client would be 'significantly handicapped' in mounting a fresh bid to overturn his conviction through the Criminal Cases Review Commission (CCRC), the independent body which investigates possible miscarriages of justice, without the evidence he sought.
Sheila 'Bambi' Caffell, who was murdered in August 1985 along with her six-year-old twin sons and the couple who adopted her, Nevill and June Bamber
Giving judgment remotely on Friday afternoon, Mr Justice Julian Knowles dismissed the latest legal action brought by Bamber in his long-running battle to clear his name.
The judge ruled: 'I am unable to say that the CPS erred in law in refusing to make the disclosure sought.'
He explained that Bamber wanted 'disclosure of material by the CPS which he says is needed so that a forensic expert can produce a definitive report which can then be submitted to the CCRC' in support of an application to refer his case back to the Court of Appeal.
But Mr Justice Knowles added: 'I am not on the material I have seen readily able to accept the premise that the existence of a second sound moderator is capable of affecting the safety of the claimant's convictions in any meaningful way.
White House Farm at Tolleshunt D'Arcy, near Maldon, in Essex, pictured, where Bamber is alleged to have shot dead his mother, father, sister and twin nephews in August 1985
'The facts are that the moderator which was found had Ms Caffell's blood in it, and she could not have shot herself when the sound moderator was attached to the rifle.'
The judge continued: 'If ever there was a case where the CCRC should be approached to make a decision on what is said to be new evidence, it is this one.
'This is a massively complex case which has been investigated and re-investigated by more than one police force over some 35 years.
'The body of material is vast. After so many years, and so much litigation, the CCRC is the body undoubtedly best placed to consider the claimant's arguments.'
Bamber previously had an appeal against his convictions dismissed by the Court of Appeal in 2002, and also had a High Court challenge to the CCRC's refusal to refer his case for another appeal rejected in 2012.