Searches are ongoing today after the discovery of partial remains suspected to be those of Danny McIlhone on a remote hillside in Co Wicklow on Saturday.
Pressure mounted on the IRA today to reveal further details about its so-called “disappeared” victims after the weekend find.
The 19-year-old vanished from west Belfast in 1981 and forensic tests are being carried out to confirm identification.
The search was carried out under the authority of the Independent Commission for the Location of Victims’ Remains which tries to find the bodies of people murdered and secretly buried by the IRA.
A spokesman for the Commission said today the searches were “ongoing”.
“They went back onto site this morning. There’s no timeframe on how long the work will take. It will take as long as it takes,”
Oliver McVeigh, whose brother Columba (17) disappeared in Dublin in 1975 after being kidnapped by the IRA, said the development offered hope to grieving families.
“It proves that people working on the ground can locate these remains provided they get the right information,” he said.
“There is no reason why others who have this information, the proper information, cannot come forward and end the families’ suffering and agony.”
The remains were found in the Ballynultagh area of Co Wicklow, where searches were carried out in 1999 and 2000 without success.
A large Garda forensic tent covers the dig area which is under round-the-clock armed protection.
SDLP Northern Ireland Assembly member Alex Attwood said: “This only confirms that serious questions still continue about the conduct of the IRA in this case of abduction and death and in all the cases of the disappeared.
“These doubts and questions must be answered in the only way possible - that all information is handed over and that those who the IRA know are withholding information are also handed over to the authorities once and for all.”
Sinn Féin president Gerry Adams welcomed the discovery.
“It is also evidence that republicans continue to work diligently on this important issue,” he added.
Mr McIlhone was named by the IRA as one of nine so-called "disappeared". One of the most high-profile cases was that of Jean McConville - a mother of ten who was murdered by the IRA during the 1970s. Her body was found buried in a beach in Co Louth in 2003.
The Independent Commission for the Location of Victims’ Remains was set up by the British and Irish governments in 1999 and reports to the Northern Ireland Office in Belfast and the Irish Justice Department in Dublin.
In April 2007, UK forensic expert Geoff Knupfer, who led the search for the bodies of the victims of the Moors murderers Ian Brady and Myra Hindley, was called in to help with new searches.
It is believed that Mr Knupfer’s work contributed to the latest breakthrough.
Sources believed the current search had been going on for at least a week and Mr McIlhone’s relatives were informed of the discovery of remains in recent days.
The excavation operation was hampered by wet and windy weather.
In 2001 the IRA claimed that Mr McIlhone was being questioned about stealing IRA weapons from an arms dump when he was killed in a struggle with a gunman who was guarding him.
The issue is expected to be discussed when Taoiseach Brian Cowen and Minister for Justice Dermot Ahern hold a pre-arranged meeting with Garda Commissioner Fachtna Murphy today.
A family spokesman said: “The commission has informed the family of the developments in Wicklow.
“We hope and pray for good news. We would ask the media to respect our privacy and stay away from the family home.”