Murdered father-of-two Benny Whitehouse had been under siege from a Traveller family because he refused to sell drugs for them, his relatives have claimed.
Whitehouse (35) was gunned down and his partner injured on Thursday after leaving their young daughter to school in Balbriggan, north Dublin.
It was the fatal final act in a series of attacks that included dropping a boulder on Whitehouse's car as he drove under a bridge while his daughters, aged four and seven, were in the vehicle.
Last week a lone gunman approached Whitehouse and his partner, Natalie White, as they got back into his car and fired point-blank through the driver's window.
Whitehouse was hit in the back, chest and hand and tried to escape through the passenger door but collapsed face down on the footpath with his legs still inside the car.
Efforts by locals to revive him were unsuccessful .
Ms White was shot in the thigh and was operated on at Beaumont Hospital as the post mortem on Whitehouse was carried out .
Whitehouse's family have denied he had any involvement in the drugs trade.
Instead, they said a campaign of intimidation by a group within the Traveller community, which started a year before his murder, was behind the fatal attack.
The gang, based in Louth and Dublin, are believed to supply drugs to criminals all over Ireland.
They are also believed to be the targets of another criminal gang who want to wipe them out.
"They accused Benny of reporting them to the gardai. This started a year ago when they started ringing a woman of the family using IRA names and trying to tax them for €30,000," said a family source who did not want to be named.
The source claimed the gang began smashing up Whitehouse's home, and that five houses were attacked to keep the pressure on him.
They also said the gang took his dogs and once tried to run him over.
The dead man's relatives admitted that members of the family had once retaliated when they tried to attack one of the gang members in an unplanned incident after a bid had been made to kidnap Whitehouse.
They believe his killer followed him to the school and lay in wait for him.
"All he lived for was his kids," said the family source, adding that Whitehouse insisted they attended school and got an education."
"Benny used to drive his kids to the front of the school. At one stage there would be gardai waiting for him.
"When all that slackened off he'd park around the corner where this happened.
"He got a different car only a few weeks ago. They were obviously following him."
The gunman escaped in a dark Ford Focus which was later found burnt-out in the Naul area of north Dublin.
It is believed he then transferred to a four-wheel-drive vehicle.