LONDON (AP) — Fifteen British soldiers who allegedly lied to an inquiry into Bloody Sunday, one of the deadliest days of the decades-long Northern Ireland conflict, will not face perjury charges, prosecutors said Friday.

There was insufficient evidence to convict the soldiers or a former alleged member of the Irish Republican Army about their testimony before an inquiry into the 1972 killings of 13 civilians by Britain’s Parachute Regiment in Derry, also known as Londonderry, the Public Prosecution Service said.

An initial investigation into the slayings on Jan. 30, 1972 concluded the soldiers were defending themselves from a mob of IRA bombers and gunmen. But a 12-year-long inquiry concluded in 2010 that soldiers unjustifiably opened fire on unarmed and fleeing civilians and then lied about it for decades.

Families of the victims were outraged by the decision. John Kelly, whose brother Michael was killed by paratroopers, spoke for the group and called it an “affront to the rule of law.”

“Why is it that the people of Derry cannot forget the events of Bloody Sunday, yet the Parachute Regiment, who caused all of the deaths and injury on that day, apparently cannot recall it?” Kelly said. “The answer to this question is quite simple but painfully obvious: The British Army lied its way through the conflict in the north.”

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Although a quarter century has passed since the Good Friday peace accord in 1998 largely put to rest three decades of violence involving Irish republican and British loyalist militants and U.K. soldiers, “the Troubles″ still reverberate. Some 3,600 people were killed — most in Northern Ireland, though the IRA also set off bombs in England.

Only one ex-paratrooper from Bloody Sunday, known as Soldier F, faces prosecution for two murders and five attempted murders. He was among the 15 soldiers who could have faced a perjury charge.

While victims continue to seek justice for past carnage, the possibility of a criminal prosecution could soon vanish.

The British government passed a Legacy and Reconciliation Bill last year that would have given immunity from prosecution for most offenses by militant groups and British soldiers after May 1. But a Belfast judge ruled in February that the bill does not comply with human rights law. The government is appealing the ruling.

Attorney Ciaran Shiels, who represents some of the Bloody Sunday families, said they would not rule out further legal action.

“It is of course regrettable that this decision has been communicated to us only today, some 14 years after the inquiry’s unequivocal findings, but less than two weeks before the effective enactment date of the morally bankrupt legacy legislation designed specifically to allow British Army veterans to escape justice for its criminal actions in the north of Ireland,” Shiels said.

Senior Public Prosecutor John O’Neill said the decision not to bring criminal charges was based on three things: accounts given by soldiers in 1972 were not admissible; much of the evidence the inquiry relied on is not available today; and the inquiry’s conclusion that testimony was false did not always meet the criminal standard of proof.

“I wish to make clear that these decisions not to prosecute in no way undermine the findings of the Bloody Sunday Inquiry that those killed or injured were not posing a threat to any of the soldiers,” O’Neill said.