The PSNI has contacted two of the most senior figures in the Army as part of its investigation into Bloody Sunday.
Detectives leading the police probe into Bloody Sunday told family members that contact with General Sir Michael Jackson and General Sir Robert Ford has already been made and they were among 450 soldiers police have identified as military personnel involved on the day.
Gen Jackson was in Derry and on the first of three tours of duty in Northern Ireland. He was present as an adjutant at the events of Bloody Sunday, when soldiers opened fire on protesters, killing 13 people.
General Ford, a Major-General at the time, was criticised in the Saville Report for deploying soldiers to arrest civilians.
In addition to the Army personnel, investigators are trying to establish the whereabouts of almost 1,000 civilian witnesses and the huge task has prompted a call for more resources and staff.
John Kelly, whose brother Michael was among those killed in 1972, said the efforts of the PSNI team was being hampered by a lack of resources.
He said: "Fair play to the detectives who are working on this investigation, they are good guys, but the sheer volume of work ahead of them leaves me wondering if this will be concluded within 10 years, never mind the two or three they think it will take.
"There needs to be more resources given over to this and more detectives appointed to get this concluded in a timely manner.
"I am glad that the team are determined that the investigation will be thorough and no one will be left out of their inquiries."
Political commentator and journalist Eamonn McCann, who has written extensively on the events of Bloody Sunday, was also in attendance when the police met with the families.
He said: "This was another frank meeting where very specific and direct questions were asked and equally direct answers were given.
"I do not recall any other circumstances where such high ranking Army officers such as General Sir Michael Jackson and General Sir Robert Ford have been contacted and asked to give accounts of their role and recollections of a day like Bloody Sunday."
Kate Nash, whose brother William was among the dead on Bloody Sunday, had quizzed the detectives about the two officers.
She explained: "This investigation is about more than the squaddies who were ordered out onto the streets.
"It is about those who sent them, too.
"It is important that Michael Jackson is questioned because he was the person who told the lie that went around the world that there were gunmen and bombers in the Bogside on Bloody Sunday."
A spokesman for the PSNI said: "The investigation is progressing and detectives have sent letters to a number of former soldiers.
"We would again encourage anyone with information to make new statements to our detectives. Civilians and former soldiers are asked to contact the investigation team on 028 9025 9593 or by email to BloodySundayEnquiry @psni.police.uk "