A fifth search has begun of a bog in Co Monaghan for one of the so-called Disappeared.
The Independent Commission for the Location of Victims Remains has announced that it has resumed the search for the remains of Columba McVeigh at Bragan Bog.
The 19-year-old from Donaghmore in Co Tyrone was abducted and murdered by the IRA in 1975.
The Commission conducted an earlier search of the bog this year, which ended without success in May.
Head of the Commission's Investigation Team Geoff Knupfer said the resumption of the search is based on a "refinement of information received.”
The Commission will also be considering the results of surveys conducted in recent months on the bog and on adjoining forested areas.
These surveys involved the use of equipment like ground penetrating radar to look for disturbances in the soil and peat to reveal where the remains might lie.
Mr Knupfer, who was also involved in the search for Moors Murder victims, said that this latest operation is a continuation of the previous one and not a new investigation.
He said he expected this search would last up to three months and today will largely be taken up with site preparation and removing trees with digging likely to begin tomorrow.
The Commission was set up to try and find the remains of the Disappeared - 17 people murdered by the IRA who then buried the bodies in secret.
The remains of nine have been found including those of Jean McConville whose remains were found on Shelling Hill Beach in north Co Louth in 2003 by a passer-by.