Wave TraumaHuman remains exhumed from a grave in County Monaghan four months ago are not those of Joe Lynskey, the organisation set up to find the Disappeared has said.
Mr Lynskey, from west Belfast, is one of the Disappeared - a group of 17 people who were abducted, murdered and secretly buried during The Troubles in Northern Ireland.
DNA test results do not match those of the family to whom the grave belongs to either, or any of the remaining Disappeared, the Independent Commission for the Location of Victims Remains (ICLVR) said.
The Irish police service, An Garda Síochána, has notified the local coroner and said inquiries are under way to identify the exhumed remains.
Northern Ireland Secretary Hilary Benn said he was "saddened to hear" the exhumation in the search for Mr Lynskey's remains has not been successful.
"My thoughts are with his family, who have faced decades of uncertainty and heartache," Benn added in a statement.
He has urged anyone who may have information that could locate Mr Lynskey's remains, or those of the remaining Disappeared, "to come forward in confidence to the ICLVR".
The ICLVR carried out the exhumation at Annyalla cemetery in November, after receiving information about suspicious activity at a grave during the 1970s.
The timeframe and the location coincided with Mr Lynskey's disappearance.
The ICLVR confirmed the outcome of tests on the remains in a statement.
It described the news as "deeply disappointing" for Mr Lynskey's family.
"The results of the DNA examination have now eliminated them as being those of the family to whom the grave belongs and now also eliminated them as being those of Joe Lynskey or any of the Disappeared," the ICLVR said.
"All the interested parties including the Lynskey family have been informed.
"We know that this news is deeply disappointing for the Lynskey family and the thoughts of everyone in the commission are with them at this most difficult time.
"We are also conscious that this was a distressing experience for the family whose grave was opened to facilitate the exhumation.
"We are grateful for their co-operation and support at all stages of the process."
The Disappeared are a group of 17 people whose bodies were buried at secret locations between 1972 and 1985.
The remains of 13 have been found so far.
The ICLVR has said it will do "everything in its power" to recover the remains of the four others.
"We would again appeal to anyone with information relating to Joe Lynskey, Columba McVeigh, Robert Nairac or Seamus Maguire to bring it to the ICLVR where it will be treated in the strictest confidence."
A former Cistercian monk from the Beechmount area of west Belfast, Mr Lynskey later joined the IRA.
Mr Lynskey went missing in 1972, and republicans have claimed he was "executed and buried" by the IRA.
The latest search for his remains was in 2018. It ended without success.
Last November, his niece said that his body "needs to be brought home".
The plight of the Disappeared has been further highlighted in recent months due to the release of the Disney+ series, Say Nothing.
The drama focuses on events during the Troubles, including the disappearance of mother of 10 Jean McConville as well as Kevin McKee, Seamus Wright and Joe Lynskey.
