12-year, 5,000-page report aiming to unlock the truth

The Saville Inquiry into the deaths of 13 civil rights marchers on Bloody Sunday is expected to exonerate the dead from involvement in violence and counter allegations from the first inquiry.

It was first commissioned in 1998 by Tony Blair after extensive calls from families of the victims to re-evaluate the incident. Its chairman, Lord Saville of Newdigate, was briefed to establish a definitive version of the events of Sunday 30 January 1972 that would supersede the first, and now widely discredited, tribunal set up by Lord Widgery in the aftermath of the shootings.

The inquiry officially opened in 2000 when formal public hearings began at the Guildhall in Derry. This culminated in public hearings on 116 days over the year, clocking up more than 600 hours of evidence from eyewitnesses.

Nearly 1,000 witnesses gave evidence, including soldiers, civilians, police, politicians, forensic experts, journalists, civilians, priests and members of the IRA, including Martin McGuinness, Northern Ireland's Deputy First Minister.

Originally scheduled to be published by 2007, the findings have been hampered by delays that have invited mounting criticism and seen costs escalate. The total cost of the investigation is now thought to be around £191m.

The 5,000-page report, which will go on sale to the public for £550, is expected to formally renounce the findings of the 1974 inquiry by Lord Widgery, that has since been widely dismissed as a "whitewash".

The report is finally set to be published almost 12 years after the inquiry was established. Family members will be able to view the report in a secure room inside the Guildhall before lining up on a stage in the square to give their verdict on its findings.