The brother of a teenager who was murdered and secretly buried by the Provisional IRA over 40 years ago says his family feel cautiously positive about a new search for his remains.
Nineteen-year-old Columba McVeigh, from Donaghmore, Co Tyrone was last seen in November 1975.
It is believed he was abducted and killed by the IRA before being secretly buried at Bragan bog near Emyvale in Co Monaghan.
The search, which begins on Monday, will be the fifth to be carried out by the Garda and the ICLVR (Independent Commission for the Location of Victims' Remains) since 1999.
Oliver McVeigh said the fresh search will be hard for his family. He said: "It is hard to get your hopes up, you just hope that something is found this time.
"We have been in this position four times before, we have learned not to expect too much too soon."
The new search will focus on an area around one acre in size.
Lead investigator Geoff Knupfer said they remain convinced that Mr McVeigh was buried at Bragan Bog.
"Over the last five years since the last unsuccessful search we have been working to refine the search area," he said.
"That is what often has to be done when we are searching for a body that has been buried somewhere in a vast expanse of bog over 40 years ago.
"That's what happened in the search for Brendan Megraw whose remains we found in October 2014 in Oristown Bog, Co Meath some 15 years after searching commenced.
"And we were close to the burial place of Seamus Ruddy in an earlier search before we recovered his remains in France in May last year.
"The fact that we are back on Bragan Bog for a fresh search does not mean that anyone who has information about where Columba is buried should assume that it is no longer relevant."
This latest search is starting on the 21st anniversary of his father Paddy McVeigh’s death. Columba’s mother Vera McVeigh died in 2007.
His parent’s grave also has Columba's name on it, in the hope that he will one day join them.
The IRA murder victim's sister Dympna Kerr said her father's anniversary had added to the "emotional turmoil" of the fresh excavation.
Mrs Kerr, who lives in Merseyside, said: "For years I couldn't bring myself to stand on that bog where we were eventually told that Columba was buried.
"I went to it earlier this year and it's a bleak and desolate place and I cannot bear the thought that Columba is out there when he should be beside our mum and dad.
"Knowing that we have the thoughts and prayers of the other families of the Disappeared gives me the strength to face the coming days and weeks.”
Out of the 16 Disappeared Columba McVeigh is one of three still missing.
Former monk Joe Lynskey and soldier Robert Nairac's bodies have also never been found.
Jon Hill, a senior investigator with the ICLVR will take charge of the initial phase of the fresh search for Mr McVeigh.
He said: "We carried out a scoping exercise earlier in the year and are now concentrating on an area of around one acre in size," he said.
"While that is relatively small compared to some of the searches we've carried out in the past, each one presents its own challenges and so I don't want to put a definitive time frame on it.
"Obviously we hope that we have an early success but if that's not the case then we'll press on for as long as it takes.
"We have a dedicated and vastly experienced team of contractors and forensic archaeologists working on the search.
"We all know what this means to the McVeigh family and we will do everything in our power to bring this search to a successful conclusion."