Investigators searching for Joe Lynskey, one of the IRA's so-called disappeared, have exhumed remains from a grave in County Monaghan.
Sky News understands the remains of "more than one person" were removed from the burial site for formal identification.
Mr Lynskey, 40, a former Cistercian monk who later joined the IRA, was abducted and murdered during a bitter internal feud in 1972.
It was 2010 before the IRA admitted he had been "executed and buried", at which point he was added to the list of "the disappeared".
The Independent Commission for the Location of Victims' Remains (ICLVR) confirmed the exhumation had taken place on Tuesday.
Read more: Investigators search for body of British soldier Robert Nairac
A spokesman said: "The Commission received information concerning suspicious historic activity during the 1970s at a grave in Annyalla Cemetery.
"Both the time frame and the location coincide with the disappearance of Joe Lynskey in 1972.
"The ICLVR did not become aware that Joe Lynskey was one of the disappeared before 2010.
"Following an exhumation, there will be a formal process to establish the identify of all of the remains found in the grave.
"This process may take some time," he added.
"The disappeared" are people believed to have been abducted, murdered and secretly buried during the Northern Ireland troubles.
In most cases, the victims were abducted in Northern Ireland but murdered and buried across the border in the Republic.
The ICLVR was established by the British and Irish governments in 1999.
Of the 16 people listed as "disappeared", the remains of 13 have been located and returned to their families for burial.
Joe Lynskey, Seamus McGuire and Captain Robert Nairac, a British Army officer, are the three cases still listed as unresolved.
(c) Sky News 2024: Remains exhumed in search for one of the IRA's 'disappeared'
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