'The Don' first came to prominence when he had his boss, Martin 'Marlo' Hyland, murdered three years ago alongside innocent young plumber Anthony Campbell.
Last night another innocent man was shot -- because he too was a witness.
Disabled Paddy Mooney (58) was gunned down at his home off Pearse Street by a hitman who then murdered his pal Brendan Molyneaux (46).
'The Don's' gang are also suspected of the murder of drug dealer John Paul Joyce, whose frozen body was found in a ditch close to Dublin Airport.
Detectives at Pearse Street arrested four people – three men and a woman – hours after the shooting last night.
Follow-up operations were ongoing in the city today.
A source described last night’s double murder as “absolutely shocking”, adding: “Paddy Mooney was murdered simply because he was in the way. No other reason.
“They shot him and then calmly walked into the flat and shot Molyneaux.”
Gardai stressed that investigations were at an early stage, but said that Molyneaux had threatened a number of Finglas men he accused of being behind the killing of his friend, Paul ‘Famer’ Martin, who was shot dead in the Jolly Toper Pub in Finglas in August 2008.
‘The Don’ and a number of his pals were among those threatened, sources said.
The murder of ‘Farmer’ Martin was carried out as part of a power struggle in the drugs trade in the Finglas area between Martin and The Don’s gang.
Coincidentally, officers on the Northside believe that murdered Traveller John Paul Joyce was shot because he failed to dispose of the murder weapon used in the Martin murder, after telling the Finglas gang he would do so. This weapon was later seized by gardai.
Despite the Martin connection, the double shooting in the city centre and the abduction and murder of Joyce are not being treated as linked.
The gang gardai suspect of carrying out the killings are suspects for a spate of gangland murders over the past four years, including the killings of major city criminals Marlo Hyland, ‘Farmer’ Martin, Roly Cronin and Graham McNally.
They are also suspected of killing innocent plumber Anthony Campbell, who, like Paddy Mooney, was shot dead because he was in the wrong place at the wrong time, as assassins went to kill Marlo Hyland in Finglas in December 2006.
The source added: “This gang are killing with impunity. They are the most violent outfit in the city and the State and have a ‘get them before they get you’ attitude.”
Last night’s attack happened at Pearse House, off Pearse Street, just before 7pm, when three men burst into the flat having called to the door.
Innocent man Paddy Mooney’s family were too upset to talk when contacted by the Herald at their Ringsend home today.
The 58-year-old was well known in his local area and was partially paralysed having suffered a stroke a number of years ago. A third person was also believed to have been in the flat at the time but was not injured.
Gardai were alerted to last night’s attack when residents heard a number of shots at 6.50pm and rang the emergency services. When gardaí and an ambulance crew arrived at the scene, they discovered the two victims with gunshot wounds.
Mr Molyneaux and Mooney were both rushed by fire brigade ambulance personnel to St Vincent’s Hospital and St James’s Hospital.
Mr Mooney was pronounced death shortly after his arrival and doctors failed to save Mr Molyneaux, who died from his injuries an hour later.
Gardai have launched a major investigation and the area around the flat was sealed off for technical examination. They are satisfied Mr Mooney had no gangland links.
Officers from Pearse Street Station have been interviewing people in the area to establish the details of the attack.
Three men and a woman were arrested in Dublin last night and were today being detained at four separate garda stations under Section 50 Criminal Justice Act 2007.
They can be held for up to a week before being charged or released. Three are in their 20s, while one of the men is in his 40s.
Distraught neighbours today peered over balconies down at flat 4G, which remained sealed off.
The door that Paddy Mooney had answered still remained open, and the doorframe and window were covered with finger-printing dust used by the garda technical bureau.
Mr Mooney’s flat, on the ground floor, is positioned right beside a small children’s playground.
“It is a terrible thing. Paddy lived here for years, he was from the area,” said one resident of Pearse House.
“We only hope that the CCTV cameras in the area might have got some pictures of whoever did this,” they added. “There was kids and all out here yesterday evening.
“There is no respect for human life any more,” the neighbour added.