Gary Carey (41) was fighting for his life last night after being targeted in a shooting for the third time in just over a year.
He was shot in the shoulder, arm, chest and leg by gunmen who it is believed had him under surveillance.
Carey has been involved in a long-running dispute with convicted killer Rattigan (42), who is now based in Spain, as well as with the west Dublin gang nicknamed The Family.
“The gang known as The Family tried to target him before, but this time the chief suspects are linked to Rattigan,” a source said.
Little has been heard of Rattigan since his release from Portlaoise Prison last August.
He was jailed in March 2003 for a number of serious offences, including manslaughter, drug dealing, firearms and assault.
If detectives’ theory is correct, it means that Rattigan, nicknamed King Ratt, has re-emerged as a significant underworld player.
Carey was found in a serious condition in the underground car park of the Hilton Hotel in Kilmainham by staff and was rushed to hospital.
It is understood he was not wearing a bulletproof vest, as he usually does, after working out in the hotel’s gym.
He was chased around the car park by at least one gunman before being shot.
He underwent emergency surgery and was described last night as being in a critical condition.
Detectives believe a silver Audi car was used in the shooting and are investigating if the gunman was waiting for Carey in the car park.
Carey, originally from nearby Islandbridge, was not staying at the hotel, and gardaí were trying last night to establish his movements before the attempt on his life.
He had been living abroad for several months before returning to Dublin in recent weeks.
Witnesses reported hearing up to eight gunshots at around 11.30am before Carey was found.
Gardaí are appealing for witnesses, especially anyone who was travelling along the South Circular Road yesterday morning, to contact them.
The victim’s younger brother, Darren Carey, was one of two men killed in the Canal Murders in 2000, which were carried out by a now dead criminal who cannot be identified for legal reasons. Darren Carey was 20 at the time.
Last November, Gary Carey was lucky to survive after being shot several times outside a house in Dublin’s Ballyfermot Crescent.
The previous March, gardaí also received reports that he had been shot at in Ballyfermot, but he escaped serious injury.
He did not make a complaint to gardaí then, but detectives believe a local criminal was involved.
Carey has been questioned a number of times over seizures of drugs, firearms and cash.
He has served only one significant jail term, for drug dealing, after he pleaded guilty at Dublin Circuit Court in 2002 and was sentenced to 15 months in prison.
A garda spokesman said the scene of yesterday’s shooting was preserved to facilitate a technical examination being carried out.