The brother of Columba McVeigh, who was abducted, murdered, and secretly buried in 1975, says "no amount of technology" will find his brother's body if "you're not sent to the right place."
There have been five searches of the Bragan Bog in Co Monaghan since 1999 and Oliver McVeigh says he is convinced there are people who have not yet come forward who could provide vital information.
During a recent Oireachtas Committee on the Implementation of the Good Friday Agreement, it was suggested that sophisticated terrain scanning technology could be useful in future searches undertaken by the Independent Commission on the Location of Victims' Remains.
However, Oliver McVeigh says inaccurate or incomplete information on his brother's whereabouts has hampered efforts to uncover his body.
While Mr McVeigh says he "leaves all the technical aspects of the searches for Columba to the ICLVR," he added that "no amount of technology will find the hole in the ground where they left our brother if you're not sent to the right place".
Oliver says the last search for his brother's body would have been successful if he "had been where the ICLVR was told he was".
He added that the ICLVR has carried out successful searches in the past, and "that tells me that the information they have been given is not accurate or is not complete and at this stage is ineffective".
Mr McVeigh says he doesn't "know why people who could end our family's 46 years torture and misery still hold back".
He added that they "won't be bothered by the police or anyone else and it may do them some good to get their conscience clear at last".
Mr McVeigh says "the last 20 years have been particularly difficult" and added that "we'll keep going because we can't rest until Columba is found and brought back to Donaghmore to rest in peace beside our mother and father".