A former British soldier will go on trial later charged with murdering two men on Bloody Sunday in Co Derry in 1972.
Soldier F is also accused of five counts of attempted murder.
He denies the charges.
He has been granted anonymity by the court.
Soldier F is accused of the murder of William McKinney and James Wray, two of the 13 people shot dead on Bloody Sunday.
They were among civil rights protesters fired on by members of the British Parachute Regiment following a march on 30 January 1972 in the city's Bogside area.
Thirteen people were shot dead on the day, a fourteenth died later.
A similar number of people were injured.
A public inquiry established by the UK government, and which reported in 2010, said none of those shot had posed a threat.
The Saville Inquiry said that the soldiers had opened fire following a loss of discipline.
Its findings were also critical of a commanding officer.
The then British Prime Minister David Cameron apologised for the conduct of the soldiers in the House of Commons.
A police inquiry followed and in 2019 Northern Ireland's Public Prosecution Service (PPS) announced that Solider F would face charges.
He was the only one of 17 former soldiers reported for potential prosecution where the PPS decided to proceed.
The case against Soldier F was later discontinued by the PPS on legal grounds but reinstated after the families took a successful court challenge.
Relatives of the Bloody Sunday dead will walk a short distance to the court for the start of the trial at Belfast Crown Court.
Supporters of Soldier F are also likely to be in attendance.
In a statement issued on behalf of the Bloody Sunday Trust, its chairperson Tony Doherty, whose father was shot dead, said they hoped for justice.
"We have waited fifty three long years...and hopefully we will see a measure of it through this trial," he said.
He said the families had campaigned for an acknowledgement of the innocence of the victims; the repudiation of results of an earlier inquiry which exonerated the soldiers and prosecutions of those involved.
Two of the three objectives had already been achieved, he said.
"This day will be a tribute to the strength of the Bloody Sunday families whose indefatigable campaign for justice has made this happen."
