On the 24th anniversary of his disappearance, Gardaí have renewed their appeal for information on Trevor Deely.
Mr Deely, who was 22 when he went missing, was last seen in Dublin.
He attended a work Christmas party at the Hilton Hotel on December 7th 2000.
CCTV footage showed him talking to an unknown male at 03.35am on Wilton Terrace on 8th December 2000.
Gardaí are still trying to identify this man as they believe he may be able to assist them with their investigation.
Mr Deely was last sighted on CCTV at 04.14am passing the Bank of Ireland ATM on Haddington Road.
He was 6ft 1”, of a slim build and with short red/brown hair and a fair complexion.
Gardaí immediately launched an investigation after he was reported missing and in May 2016, Pearse Street Garda Station renewed the investigation.
That investigation continues, and Gardaí have urged anyone with information to come forward.
They say "even the smallest piece of information, which may seem insignificant" could help with the investigation.