Families of the victims of the infamous 1972 Bloody Sunday killings in Northern Ireland marched to the courthouse before the trial of the only person ever charged in the massacre.

The families, who have campaigned for more than half a century for accountability for the killings, carried photos of the dead and walked behind a banner reading “Towards Justice.”

The ex-paratrooper known as "Soldier F" has pleaded not guilty to two counts of murder and five counts of attempted murder in the Belfast court.

Prosecutors say the killing of 13 unarmed civil rights demonstrators and wounding of 15 others was unjustified.

The Jan. 30, 1972 massacre in Derry has come to symbolize the long-running conflict between mainly Catholic supporters of a united Ireland and predominantly Protestant forces that wanted to remain part of the UK.

Tensions have eased since the 1998 Good Friday peace accord, which created a system for Republican and Unionist parties to share power in Northern Ireland.

The government initially said soldiers from a parachute regiment opened fire at gunmen and bombers who were attacking them.

A formal inquiry cleared the troops of responsibility.

A subsequent and lengthier review in 2010 reached a much different conclusion, finding that soldiers had fired at unarmed people fleeing and then lied about it for decades.

Then-Prime Minister David Cameron apologised and said the killings were “unjustified and unjustifiable."

The findings cleared the way for the eventual prosecution of Soldier F, though that, too, has been beset by delays and obstacles.

It took seven years from the time police opened their investigation until prosecutors announced in 2019 that they would only charge Soldier F.

They said there wasn't enough evidence to charge 16 other former soldiers and two alleged members of the Official Irish Republican Army who were investigated for their roles in the shootings.