LONDON (AP) — A British judge ruled Wednesday that a 67-year-old Irishman was an “active participant" in the 1982 IRA nail bombing attack in London's Hyde Park that killed four soldiers.

The decision came in a civil suit that relatives of the dead launched some five years after a criminal case against John Downey collapsed. Judge Amanda Yip ruled that Downey was responsible with other IRA members for the attack on the Household Cavalry in which 31 other people were injured.

“This was a deliberate, carefully planned attack on members of the military,'' Yip said. “I have found that the defendant was an active participant in the concerted plan to detonate the bomb, with the intent to kill or at least to cause serious harm to members of the Household Cavalry.”

The ruling will make it possible for the families to sue Downey for damages.

The criminal case collapsed after it emerged that the British government misled Downey into thinking he could travel to England without fear of arrest. The Northern Ireland Office gave Downey a confidential document saying he was not wanted for any outstanding IRA crimes.

The case shed light on the secret practice of providing letters promising safe passage home for scores of IRA members who had fled Northern Ireland to avoid arrest and remained fugitives, living for decades mostly in the Irish Republic.

The Irish nationalist Sinn Fein party had demanded that Britain let such IRA members return to Northern Ireland as part of wider peacemaking efforts. Former British Prime Minister Tony Blair's Labour government agreed but failed to get the measure passed by the House of Commons.

So instead it adopted the use of secret letters. Until then, the public had been led to believe that IRA fugitives from justice had remained on Britain's wanted list.

The lawyer for Sarahjane Young, the daughter of one of the Household Cavalry victims, said justice had prevailed.

“Sarahjane, and the families here today, were told they'd never get justice, that they should put the past behind them and move on,'' said the attorney, Matthew Jury. "They and thousands whose lives were devastated by the IRA are the forgotten victims.''

Downey is now in prison in Northern Ireland, awaiting trial for another attack during the deadly Troubles period.

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