The man leading the search for the remains of a murdered Sunderland soldier insists there is still "plenty going on behind the scenes".
May 15 marks the 42nd anniversary of Captain Robert Nairac's death at the hands of the IRA.
Captain Nairac, 28, who worked in military intelligence, was kidnapped from a pro-Catholic pub in Northern Ireland on May 14, 1977, and taken over the border to the Republic of Ireland where he was shot in the early hours of the following morning.
Six people were later convicted of their part in his murder although none disclosed what happened to his body.
The Sunderland-raised soldier is now one of only three people to "disappear" during Ulster's bloody Troubles whose remains have still to be found.
Geoff Knupfer, the lead investigator for the Independent Commission for the Location of Victims' Remains (ICLVR), said: "There is certainly plenty going on behind the scenes, which I can't discuss openly at this stage, so we have certainly not given up hope.
"We are not interested in how people know information. We are not passing information on to any other authority.
"All we are interested in is recovery so that his family can give him a Christian burial."
Mauritius-born Captain Nairac lived with his family in Thornhill Gardens, off Tunstall Road, Ashbrooke, for around 20 years.
He attended Roman Catholic public school Ampleforth College, on the North Yorkshire Moors, and Oxford University before joining the Grenadier Guards.
Increasingly working undercover in Ulster as part of his military intelligence role, he reputedly sang Republican songs in the staunchly Catholic Three Steps pub, in Dromintee, South Armagh, before he was abducted by the IRA and executed.
Mr Knupher has repeatedly discounted rumours that Captain Nairac was fed to an industrial mincer and believes he is buried in the vast County Louth countryside.
He added: "Until we have that extra piece of information then we are not in a position to begin digging."
The ICLVR, which cannot by law pass information on to other authorities, can be contacted in confidence on 00800 55585500 or via email at Secretary@iclvr.ie.
Further details are available on its website here.