The organisation set up to find those known as the Disappeared is mapping a bog in County Meath.
The Independent Commission for the Location of Victims Remains (ICLVR) is carrying out the work in Oristown in relation to one of those kidnapped and murdered by the IRA, Joe Lynskey.
Mr Lynskey, a former Cistercian monk from west Belfast, who later joined the IRA, went missing in 1972.
The body of IRA victim Brendan Megraw was found in Oristown last month.
His remains were found in a drainage ditch on Oristown bog, near Kells, by contractors called in to prepare the site for forensic excavations.
DNA tests positively identified the remains as those of Mr Megraw.
Mr Megraw was 23 when he was abducted from Twinbrook in Belfast in 1978, and murdered by the IRA.
He had recently been married and was awaiting the birth of his daughter.
His kidnappers had drugged his wife, Marie, in their home as they waited for his return, and as they took him away they warned her not to worry or contact police.
Separate searches have also taken place on bogland a few miles away from where Mr Megraw was buried in County Meath for the remains of Kevin McKee and Seamus Wright, both of whom were abducted by the IRA in October 1972.
It is also suspected Mr Lynskey, from the Beechmount area, was also buried somewhere in the region.
The news about the mapping emerged on Thursday, as commissioners Sir Ken Bloomfield and Frank Murray and families of the Disappeared gathered to make an appeal for more information on the six outstanding cases.
Mr Murray said the Commission was "now starting preliminary work at a very early stage" in relation to Mr Lynskey.
"We are information led," he added. "We do not carry out speculative searches.
"But where we have information that is judged to be credible we will act on it.
"Like Ken I completely understand the frustration of the families who have had to endure this pain for too many years.
"But as the recovery of Brendan shows, original information that did not produce a positive result is not necessarily wrong: it needs to be refined.
"And that is why it is important to join the families to appeal for more information on the six outstanding cases."