The man shot three times through the front door of his west Dublin home was gunned down in front of his young son.
Willie O'Brien (32) was hit in the chest, shoulder and hand when a gunman opened fire on him at Beechfield Rise in Ongar, west Dublin, at around 10am yesterday morning.
He was rushed to Connolly Hospital in Blanchardstown where he underwent surgery to remove bullets, one of which was lodged in his abdomen.
Gardai say the high level of organisation involved in the hit means they are investigating an attempted murder.
"You could only think this was meant to be a murder when you see the evidence such as the type of weapon involved and an organised getaway," said one source.
It is believed that a 9mm handgun was used in the shooting and that O'Brien opened the door to the gunman and shut it when he realised his life was in danger, but the gunman fired through it before fleeing.
After the shooting, the gunman escaped in a silver Ford Galaxy car that was later found burned-out in the nearby Phibblestown Woods estate.
Investigators believe the gang switched to another car in this quiet cul de sac and made their getaway.
Meanwhile, O'Brien's family has said he was shot in front of his young son in the attack.
"He was shot in front of his young lad. It's just not on," said one man at the family home in Dublin city centre.
A family friend said that O'Brien's mother was too distressed to talk.
One theory being investigated is that O'Brien was targeted by a major Dublin criminal who was monitoring his movements.
O'Brien's car was also previously burned-out when it was parked outside a friend's house in East Wall in June 2010.
Neighbours in Beechfield Rise said O'Brien largely lived a quiet life, not drawing attention and getting on with life with his partner and child.
Three bullet holes at chest and body height could clearly be seen in the glass panes of the front door, with a fourth bullet going through a side glass panel at knee height.
In a separate unrelated shooting incident yesterday, two homes were struck by gunfire in Rathmines.
Nobody was injured in that incident but a baby escaped unharmed.