Mark Burcombe, (27), from Ballynahinch Road in Lisburn, had originally been charged with the murders of Andrew Robb, (19) and 18-year-old David McIlwaine.

The Portadown teenagers were found dead at a roadside just outside Tandragee in February 2000.

However, two months ago Burcombe offered to turn Queen's evidence in return for the lesser charge of conspiring to cause grievous bodily harm to Andrew Robb.

He appeared at Belfast Crown Court last Friday where he pleaded guilty to the charge and was jailed for two-and-a-half years.

It is expected he will be released soon as he served his sentence under remand.

Paul McIlwaine, David's father, described the judgement as "shocking – a disgrace".

He said, "That's just the way it has been since day one. I'm angry but I'm not surprised to be honest.

"Both families believe he should have been tried for double murder. He was due to appear in court for murder so there was no reason for him to receive a lesser charge."

Meanwhile Andrew Robb's mother Ann declared the sentence was not justice for her son's death.

"I'm disgusted, sick to the backbone that this can happen in a supposedly civilised country," she said.

When passing his sentence, Mr Justice Hart said that Burcombe was entitled to additional credit, "however unpalatable it may be", because he had given evidence against former co-accused Steven Brown, from Castle Place in Castlecaulfield.

Burcombe will now be put forward as a 'witness of truth' in Brown's trial which is due to start in November.

Mr Justice Hart added that under the Serious Organised Crime and Police Act he was required to take into account Burcombe's assistance to police and decision to give evidence.

charges

He added that Burcombe could not be sentenced on the charges of murder when he had pleaded not guilty and the charges were not proceeded with.

Instead Burcombe claimed in a 43-page statement that Brown, together with another man, Noel Dillon, who committed suicide in 2005, murdered the teenagers after one of them supposedly made "dismissive" comments about the murder of alleged UVF man Richard Jameson.

He also claimed he told McIlwaine, "They're going to give Robb a beating for slabbering about Jameson. Don't worry, it's nothing to do with you."