Gardaí in Dublin believe that a 23-year-old man shot dead in the Kilbarrack area of Coolock over the weekend may have been the unintended victim of a gangland-style assassination attempt on one of two other men who were present when he died.
They last night released without charge a 24-year-old man arrested nearby four hours after the murder on suspicion of being in possession of a firearm.
Garda technical experts are continuing to examine two vehicles seized at the house in the Coolock area where he was arrested.
Keith Fitzsimons, from Glin Grove in Coolock, was killed after two men approached him and two others as they chatted in the garden of a house at Millbrook Road, Killbarrack at about 11.15pm on Friday.
One of the men produced a handgun and fired seven shots at the group from the right-hand side, hitting all three.
Mr Fitzsimons was hit in the leg, abdomen, arm and chest, and died instantly. A postmortem examination has since revealed that the fatal bullet went through the right side of his chest before proceeding to the left side and shattering his heart. Another bullet broke his arm.
The two other men were also hit but their injuries are not life-threatening and one was released from hospital shortly afterwards.
Mr Fitzsimons is the fifth person to be murdered in the area since Christmas, and the third to have died within a one-mile radius during that time.
The two other men who were with Mr Fitzsimons when he was killed are in their 20s, are residents of the area and are known to gardaí. They are believed to have strong links with local criminal gangs involved in drug dealing and armed robbery.
One of the men has recently been the subject of a similar attempt on his life, and is thought to have been the intended victim of the attack. Officers questioned this man last night and expect to question the other man later today.
They are also examining seven bullet casings found at the scene to see if they are linked to guns used in other crimes in the city.
While Mr Fitzsimons had some minor public-order convictions, he was described as by "no means a major player" and an innocent victim of the attack.
The shooting late on Friday night took place after an earlier altercation outside a pub on nearby Edenmore Avenue. The two men who were with Mr Fitzsimons when he was killed were involved in this altercation.
However, Mr Fitzsimons was not present at the time of this altercation.
Superintendent Noel McLoughlin of Coolock Garda station yesterday appealed for locals, as well as any friends and associates of the two men who were with Mr Fitzsimons at the time of the shooting, to come forward with information.
"People are not living in fear here, but we need people to stand up and be counted and come forward to us," he said.