Gardaí believe the murder in Finglas, Dublin, yesterday of Martin "Marlo" Hyland was carried out by a former drug dealing associate from north Dublin who had close knowledge of Hyland's varied movements and living arrangements.
Detectives working on the case also say the killers most likely used a silencer on the handgun used to shoot Hyland and young plumber's apprentice Anthony Campbell, from Dublin's north inner city.
Mr Campbell (20), of Michan's House flats, Greek Street, Dublin 7, was shot in the head in the living room of the house at Scribblestown Park where he was carrying out work when the killers arrived.
Gardaí said he was "tragically in the wrong place at the wrong time".
Investigating officers believe those who called to shoot Hyland unexpectedly happened across Mr Campbell in the house and decided that as a potential witness he should be killed. It was not clear who was shot first.
Hyland was asleep upstairs when the killers arrived. He was shot in the head at least twice as he lay in bed.
Garda sources last night said Hyland (39) stayed between a number of houses he owned in west Dublin, most of which are in the Cabra and Finglas areas.
They say the people who carried out the killing would have to have known not only the locations of the houses but also Hyland's movements between the properties, suggesting the involvement of people who had until recently been very close to him.
"Obviously they knew the minute he started sleeping at this house, kept an eye on him and carefully planned this murder," said one informed source.
Gardaí believe Mr Campbell and the plumber he worked for called to the townhouse at Scribblestown Park at about 8.30am to begin work. They were working for Hyland's niece, who lives in the house with her young children.
Some time about 9am Hyland's niece left the house with her children. Around the same time the plumber carrying out the work also left the property in his silver Renault Traffic van to collect supplies, leaving his apprentice Mr Campbell to continue working alone at the property.
Hyland's niece and the plumber returned separately to the house after 9.30am to find the two men shot dead. Gardaí were alerted immediately. The scene was sealed off and a full technical examination was carried out.
The remains of the two victims were taken by private ambulance from the scene and postmortems by State Pathologist Prof Marie Cassidy on both were expected to be completed late last night.
At about 10am yesterday gardaí received reports that a black Volkswagen Passat, registration 06 D 77432, was on fire in the Ballygall area of Glasnevin. They believe this was the car used by the killers.
The house at Scribblestown Park is part of a small development of social and affordable housing that has been built in the past two years. It is located off Ratoath Rd, Finglas.
Supt Gabriel McIntyre, who is leading the double murder investigation, said Ratoath Road carried a large volume of morning rush hour traffic.
He appealed to any motorists who might have seen any vehicle, particularly the black Passat, being driven erratically or at speed in the area yesterday morning to contact gardaí.
They believe the car might have used a number of other main roads between 8.30am and 10am including Griffith Avenue Extension, Finglas dual carriageway and Ballygall Rd, where the Passat was found burned out near the Quarry Pub.
Gardaí at Finglas can be contacted on 01-6667500.
