Gardaí are continuing to question the 32-year-old driver of a car in which the 27-year-old passenger was shot dead in Clontarf on Tuesday night as part of a feud between two south Dublin criminal gangs.
Forensic specialists are examining a handgun which gardaí believe is the murder weapon and the getaway car, a beige Peugeot 307, which was abandoned in nearby Furry Park.
Gardaí are still trying to trace the movements of that car since it was stolen three weeks ago and are appealing for anyone who may have seen it to come forward.
The post mortem on the body of the victim, Noel Roche, has shown he was shot once in the head and twice in the body.
Meanwhile, detectives investigating last Sunday's double murder at Firhouse in south Dublin believe it is likely that Darren Geoghegan and Gavin Byrne were set up and killed by people they knew and trusted and not paramilitary or former IRA hitmen.
Detectives believe the only way to stop these tit-for-tat killings is for people close to the gangs - their associates, families, relatives and friends - to give gardaí the information they need to solve the murders.
