Gardaí investigating the double murder of Brian Downes and Edward Ward last month believe they have found the motorbike used in the attack.
The 1100cc bike was found in the Grand Canal near Kylemore Road, Bluebell, Dublin, during a search last Friday.
Gardaí searched the portion of the canal after they learned the motorbike carrying the murderer escaped through that location after the double killing.
When the bike was found its details were checked on the Garda's Pulse computer system to determine if it had been reported stolen.
The database search revealed that two men had been stopped on the bike by gardaí before Mr Downes and Mr Ward were shot dead on October 5th.
It is understood the men told the gardaí who stopped them that they had just bought the bike and had not yet registered it. Their names and addresses were taken and were entered on the Pulse system.
After the bike was recovered gardaí decided to arrest the men to question them more closely about the bike's history.
The men were arrested on Saturday morning and were taken for questioning to Sundrive Road Garda station in Crumlin. They were both detained under Section 30 of the Offences Against the State Act.
One of them, a 28-year-old from Finglas, was released without charge yesterday morning. A 27-year-old, also from the Finglas area, was still being questioned last night.
Senior Garda sources said while the men are not being treated as prime suspects in the double killing they are regarded as sources that could lead the investigative team closer to the killer and his driver on the night.
Brian Downes (40), Kingswood, Tallaght, and Eddie Ward, a 24-year-old from Clondalkin, were shot dead at Mr Downes's mother's home on Greenhills Road, Walkinstown.
Gardaí are satisfied Mr Downes was the target of the gun attack and was killed by gangland figures with whom he associated. They believe Mr Ward had called to see Mr Downes and was caught up in the attack.
Mr Downes, a second-hand car salesman, was known to supply cars to criminals which were used in the commission of crimes. When 27-year-old Drimnagh man Noel Roche was shot dead in November 2005 in Clontarf, Dublin, Mr Downes was questioned by gardaí in the context of allegedly supplying a vehicle to the killers.