One of the men challenging a verdict that he is liable for the Omagh bombing was a self-confessed Real IRA terrorist, the Court of Appeal heard today.
Counsel for victims' relatives claimed Seamus Daly's admitted subsequent role in the organisation was further proof that he was properly held responsible.
Senior judges were also told that Colm Murphy, a second republican bidding to overturn a finding against him, was a liar whose phone was indisputably in Omagh on the day of the attack.
Both Daly, from Culaville, County Monaghan, and Murphy, a Dundalk-based builder and publican, are appealing a second High Court verdict which identified compelling and overwhelming evidence of their connection to the massacre.
Twenty nine people, including the mother of unborn twins, were killed in the August 1998 outrage. Hundreds more were badly injured.
No-one has ever been convicted of carrying out the bombing in a criminal court.
But relatives of some victims brought a landmark civil action against those they suspected of being connected.
Murphy and Daly have already successfully appealed once against being held responsible in an initial ruling in 2009.
Two other men, convicted Real IRA leader Michael McKevitt and fellow dissident republican Liam Campbell, failed to have the findings against them overturned.
At the retrial the judge decided on the balance of probabilities that Daly called Mr O'Connor on the day of the bombing on one of the phones allegedly supplied by Murphy.
Lawyers for the two appellants have claimed they were denied a fair hearing.
Murphy's legal team also contended he should not have been held liable based on his failure to testify.
But opening the Omagh families' case, Brett Lockhart QC argued that the retrial judge had delivered a comprehensive and rational verdict.
The barrister said: "It did not deserve the kind of aspersions that were cast at it in relation to subconscious bias, cognitive bias or being coloured."
Mr Lockhart insisted that "obvious omissions" in the first trial were no longer present the second time round.
Dealing with the case against Daly, he pointed to his guilty plea in 2004 to being a member of a terrorist organisation in 2000 - a factor in the civil verdict against him.
Mr Lockhart told the court: "We were very clear that we were dealing with a man who was a self-confessed terrorist for the Real IRA well after the Omagh bombing, not before it.
"Despite the atrocity he decides he's going to be a member."
It was set out how Daly's plea covered only a specimen offence dealing with a single day.
"I think it's unlikely he was an associate member for one day," the barrister submitted.
Turning to Murphy, he noted the only evidence from him emerged from Garda interviews.
"There can be no argument that he lied," Mr Lockhart said.
"His phone is indisputably in Omagh and he told the Garda something different."
He emphasised how Murphy's phone was traced to Omagh and also to the south Down area on the same day as a bomb attack in Banbridge three weeks earlier.
Mr Lockhart asked: "What are the chances, on the days of two bombings that it just so happens to be at the site or close to the site of the bombings?"
The appeal continues.