On 30th January 1972, thousands of civil rights demonstrators carried out a planned march through the streets of Londonderry in protest against a decision by the British government to imprison IRA suspects without trial.
Shots were fired by soldiers from 1 Parachute Regiment and in the 18 minutes that followed, 27 people were injured, 13 of those died.
In an inquiry the soldiers involved maintained they were simply returning fire from the crowds, believing those killed were bombers and a threat to them.
The families say they were innocent.
Michael Kelly was one of the men shot and killed. His brother John told Forces News he wants to see the soldiers implicated jailed, saying it would be a relief if prosecutions are brought against them.
The former personnel, who are now in their sixties and seventies, are being represented by Devonshires Solicitors.
Philip Barden from the firm says if legal action is started, the process could take years.
"These are people who, on a daily basis, are scared for the safety of their families."
"You can imagine the stress that has on individuals, it could be intolerable", he added.
The Ministry of Defence has confirmed it will cover the costs of the ex-soldiers’ legal representation, and says it is committed to providing high quality welfare and support.
Former Chief of the General Staff Lord Dannatt raised concerns about the implications any prosecutions in Londonderry could have on others.
"Occasionally things will go wrong and occasionally there are allegations that are made or investigated and there is evidence to back them up."
"What worries me more is the wholesale allegations that have been made in Iraq and Afghanistan, and more recently in Northern Ireland, and the widespread threat that soldiers could well get a knock on the door. It has really got to be gripped by the Westminster government and protocols to be put in place."
The families in Bogside Londonderry, however, say prosecutions would bring closure to a community that has been defined by death.
The decision is expected to be made on Thursday morning.