Excavation work has begun at a site sealed off by gardaí investigating the disappearance of Trevor Deely almost 17 years ago.
The search began on Saturday after detectives received new information.
A three-acre site at woodland in Chapelizod was cleared over the weekend.
Mr Deely, from Naas in Co Kildare, was 22 when he went missing while walking home in south Dublin following a Christmas party in December 2000.
Gardaí are acting on new information received during a complete review of his disappearance by a cold case review team set up last December in Pearse Street Garda Station.
Gardaí are investigating if Mr Deely was killed by a known criminal whom he may have met by chance in the Baggot Street area.
While detectives have been following a number of lines of inquiry since the review team was established, they are treating this information very seriously.
The search is being led by a forensic archaeologist and is expected to take a number of weeks.
