Gardai investigating the site identified as missing man Trevor Deely's grave, by a criminal turned informant, have discovered a firearm.
The weapon was found yesterday at the dig site in Chapelizod, in west Dublin.
The source had told gardai Trevor was shot and buried at the site, following a chance encounter with a Crumlin criminal.
And the discovery of the gun has added to fears that this version of events will prove to be correct.
However, officers will have to work to establish the connection between the firearm, Trevor's disappearance and, alleged murder.
The suspect identified over the alleged murder is part of a Crumlin crime family responsible for bringing a contaminated consignment of heroin into Dublin from the UK in the 1980s.
It was a consignment that led to the deaths of a number of heroin addicts in the city.
While heavily involved in the prostitution trade and drug dealing scene in the Baggot Street area in the 1990s, the family-based gang are no longer players in the gangland scene.
The informant, who has alleged a member of the crime family shot and buried Mr Deely, came forward due to a guilty conscience, gardai believe.
Mr Deely was 22 when he vanished following a night out in Dublin city centre almost 17 years ago.
Following the recent tip-off, gardai prepared a search of a three-acre wooded site in Chapelizod.
Officers have divided the search area into four separate zones. They have been slowly working their way to the area identified as Mr Deely's grave by the informant.
It is understood they avoided digging directly on the site in order to ensure no evidence is damaged.
The Bank of Ireland worker was last seen in the early hours of December 8, 2000, in the Haddington Road area of the city centre.
The last known images of him were captured by a CCTV camera at the junction of Haddington Road and Baggot Street at 4.14am.
A man dressed in black, who gardai believe also spoke to Mr Deely outside his place of work minutes previously, can be seen following him in the direction of Haddington Road.
This footage was only made public earlier this year after a specialist unit, set up in Pearse Street garda station to review the case, secured improved CCTV images.
The individual, who has given information to gardai, has not supplied any motive for the alleged murder of Mr Deely, but claimed that he was killed after having an interaction with the Crumlin criminal on the morning of his disappearance.
Officers said information suggesting Mr Deely's body has been buried in the three-acre site at Chapelizod was being treated as credible.
It contained considerable detail and came from a source that had been assessed by officers before a decision was made to carry out a search of the area.
"This is a line of inquiry that has to be fully pursued until we are satisfied we have made every effort with it and there is a chance that it could produce a result," one officer said.
Gardai said the source was not influenced by the offer last April of a €100,000 reward for information when deciding to step forward after such a long gap and make contact with investigators.
But the fresh information was confined to the location of the site and the possibility that Mr Deely's body could have been buried there.
Officers said it was not linked to any leads that had been examined in the past.
As the dig got under way this week, the continuous flow of gardai entering the sealed-off woodland marked just how extensive their recent search has become.
A black canvas stretching across the site, along with a large density of trees, separated the high profile operation from the Lucan Road.
At one stage on Monday, several large empty bins were taken off a truck and pushed on to the site.
Heavy excavation machinery has also been posted at the site.
It is understood officers have been preparing for a long operation at the site, which could even run into months.