A CONVICTED killer found guilty of brutally murdering his family has applied for evidence to be disclosed which he says could allow him a third appeal.

Jeremy Bamber was jailed in 1986 for the murders of his parents Nevill and June, his sister Sheila Caffell and her six-year-old twin sons, Nicholas and Daniel, at White House Farm in Tolleshunt D’Arcy.

But now lawyers working on behalf of Bamber have contacted the head of special crime and counter terrorism division at the Crown Prosecution Service, Sue Hemming, asking for documents to be disclosed which he believes could prove his innocence.

Bamber believes evidence was taken from two sound moderators rather than one.

He has consistently declared his innocence claiming Sheila, who had mental health problems, killed the family before turning the gun on herself.

The prosecution in the 1986 trial argued it could not have been Sheila because she could not have killed herself while the sound moderator was on the gun because her arms were simply too short to have reached the trigger.

She could also not have returned it to the gun cupboard at the farmhouse.

However, Bamber is contesting the sound moderator evidence and is calling for disclosure of information.

Bamber, 57, says there is evidence more than one sound moderator was examined and the findings were merged - and as such contaminated - before being presented at trial.

In a letter sent from HMP Wakefield, a Category A prison where Bamber is serving a full life tariff, he said: “Once the CPS formally disclose these documents it is an admission Essex Police took two silencers to the lab for examination, both had areas of blood staining on them and both were ruled irrelevant to the inquiry.

“Sue Hemming has to conceded to the Criminal Cases Reviews Commission the CPS can no longer sustain my conviction and my case must be fast tracked to the Court of Appeal.

"The CPS cannot sustain my conviction now the second silencer should have been known to the jury.”

Bamber has had two appeals against his conviction in 1989 and 2002, both of which were rejected by the Court of Appeal. In 2012, the Criminal Cases Review Committee rejected his bid for a third appeal.

A spokesman for the Crown Prosecution Service said: “We have received correspondence in relation to this matter which is under consideration.”