Gardaí investigating the double murder in Walkinstown, Dublin, are studying the criminal background of one of the victims in an effort to establish a motive for the killings.
Detectives believe the attack was elaborately planned and carried out by an experienced gunman.
Brian Downes (40), with an address at Kingswood, Tallaght, and Eddie Ward, a 24-year-old from Clondalkin, were shot dead at Mr Downes's mother's home just before 10pm on Friday.
The murders were the 12th and 13th gangland style killings so far this year.
Minister for Justice Brian Lenihan is to meet with Garda Commissioner Noel Conroy this morning to discuss the Garda's response.
A lone gunman is believed to have travelled to the murder scene by motorbike on Friday night before discharging at least 10 shots from an automatic pistol.
Both men were shot several times as they stood outside the house. The gunman sped from the scene on his motorbike. The victims were taken by ambulance to St James's Hospital and Tallaght hospital but died late on Friday night.
Mr Downes's three children and mother were at the house at the time of the shooting.
It is understood that his six-year-old daughter ran to her father as he lay on the ground after being shot.
Gardaí are satisfied Mr Downes was the target of the gun attack. They believe Mr Ward had called to see Mr Downes and was caught up in the attack when the killer struck.
Mr Ward at one time worked selling cars for Mr Downes, but had recently established his own business in the motor trade.
Reliable sources told The Irish Times that while Mr Downes, who was separated from his wife, was known to gardaí, there was no intelligence to suggest that he was at risk of being murdered.
The secondhand car salesman was known to supply cars and vans to criminal gangs which were used in the commission of crimes or as getaway vehicles for shootings. When 27-year-old Drimnagh man Noel Roche was shot dead in November 2005 in Clontarf, Dublin, Mr Downes was questioned by gardaí.
He was questioned in the context of allegedly supplying a vehicle to the killers. Roche was gunned down as part of a feud between rival gangs in Crumlin and Drimnagh which has claimed 10 lives since 2001.
Mr Downes was also suspected of laundering money for his criminal associates. However, sources said there was no "hard and fast" evidence of the alleged money laundering.
Detectives believe an analysis of the dead man's financial records may shed light on the extent of his involvement in organised crime, and possibly on the identities of those he was working with.
Senior Garda sources said they could also not rule out the possibility that killings were carried out after Mr Downes became embroiled in a personal dispute with a former criminal associate.
They also believe a former paramilitary figure was trying to extort money from him.
"He had a finger in lots of pies, so it's a question of take your pick when it comes to motive," said a senior Garda source.
Mr Downes ran his car business from the house where he was shot dead and also from a property he owned at St Brigid's Cottages near the M50 roundabout.
In 2003 he appeared in court after he allowed 13 Traveller families to park their caravans and live at a site at the back of his house at St Brigid's Cottages.
He also used the site as an unlicensed lorry container storage facility.