A search of three acres of woodland in Chapelizod began yesterday after detectives received new information.
He was last seen on CCTV footage crossing Baggot Street Bridge and heading towards Haddington Road in Dublin city centre.
It is understood the information was passed to investigating detectives at Pearse Street Garda Station by a close associate of a Dublin criminal in recent months.More news: Trump to declare opioid crisis a national emergency
His family have also been involved in a litany of crimes including firearms offences and the sale and supply of drugs.
The file on Trevor Deely has never been closed and there have been a number of appeals for information over the years but Trevor has never been found.
Mr Deely, who was 22 and working as an employee of Bank of Ireland when he vanished, was not known to the people gardaí suspect killed him and concealed his body.More news: Vin Diesel to Star in 'Fast and Furious' Live Arena Tour
This criminal gang has also been investigated for the unsolved murder of 21-year-old prostitute Sinead Kelly in the same locality.
Speaking at the Chapelizod search site sealed off over the weekend, Det Insp Paul Costello said that gardai would be keeping an "open mind" as the examinations developed.
Moments later, Mr Deely could be seen arriving at the rear gates of the bank offices followed by the man, and the two of them have a brief conversation.More news: Arsene Wenger admits potential 'mistake' in delaying Arsenal talks
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