Two dissident Irish republicans were found guilty yesterday of murdering a police officer who was gunned down in Northern Ireland three years ago.

The pair did not testify on their own behalf and the court heard they had not answered a single question during a total of 79 interviews by detectives investigating what the judge called a "callous and cowardly crime".

PC Stephen Carroll, 48, was shot dead when he and his colleagues were lured by a fake 999 call to a housing estate in Craigavon, County Armagh, which is a centre of dissident activity. He was the first member of the Police Service of Northern Ireland, which replaced the Royal Ulster Constabulary, to die violently.

A political crisis developed at the time of the incident, which happened just days after two soldiers died in another dissident attack in Co Antrim. But the deaths did not disrupt the peace process, instead producing unprecedented demonstrations of political and communal unity.

PC Carroll, a Catholic originally from the Irish Republic, who was married with children, had been a police officer for more than 24 years. He was in an unmarked patrol car when a bullet fired by a sniper lying in wait hit him in the head, killing him instantly.

One of the two men convicted, Brendan McConville, 40, of Craigavon, is a former Sinn Féin councillor who defected from mainstream republicanism to a violent dissident group, the Continuity IRA.

The second man is John Wootton, 20, from Lurgan. Both will automatically receive life sentences, although the judge has yet to specify how many years they should serve.

On hearing the verdicts, the constable's widow, Kate, who attended almost every day of the nine-week hearing, embraced her son and, outside the court, hugged her husband's colleagues.

She said: "I'm very happy that this is all over. I'm so relieved. It's been such an ordeal. Justice has been done.

"I feel pity and disgust for them because we are trying to move on in Northern Ireland. I pity them more than anything else. They have achieved nothing. They are fighting a losing battle. Why do they do it? No one wants it any more."

She and her husband had already been making plans for his retirement, which was due in 2011.

Matt Baggott, the Chief Constable of Northern Ireland, praised the bravery of the Carroll family. The court heard that Wootton had sought information about another officer, and when he was told police did not deserve to die had responded: "A cop's a cop."