Public hearings into allegations of historical child abuse in church and state-run homes in Northern Ireland will begin later today.
An inquiry headed by a former senior judge is examining the extent of wrongdoing in children's homes, orphanages, industrial schools, workhouses, borstals, hospital units and schools for young people with disabilities. Many were run by religious orders which at the time largely evaded scrutiny.
Sir Anthony Hart's probe was ordered by Northern Ireland's ministerial executive after the problem was found to be endemic across similar institutions in the Republic of Ireland and claims of mistreatment of victims north of the border.
The expert panel will investigate whether sexual, emotional or physical harm was inflicted upon children and if there were systemic failings by institutions or the state in their duties towards children in their care between 1922 and 1995.
More than 300 witnesses from Northern Ireland, Australia, the Republic of Ireland and Great Britain are expected to give evidence.
Two Londonderry homes run by Sisters of Nazareth nuns will be the focus of early inquiry sessions, St Joseph's at Termonbacca and Nazareth House on Bishop Street.
Chairman Sir Anthony is expected to give an opening address today, followed by a general overview of the questions and issues to be addressed from legal counsel to the inquiry Christine Smith QC, which is expected to last until Wednesday.
The inquiry is likely to hear evidence from more than 300 witnesses. Most will give evidence in person, although some may only submit a written statement.
The inquiry hopes to finish taking evidence by June 2015. It is scheduled to complete its report and present it to the Office of the First Minister and deputy First Minister by January 2016.
The chairman is a retired senior judge who practised in Northern Ireland. The other members of the inquiry panel are Geraldine Doherty, formerly the head of the Central Council for Education and Training in Social Work in Scotland, and David Lane, formerly director of social services in West Yorkshire.