Gardaí in Clondalkin, west Dublin, said Mr Damien Dowdall was not a criminal himself and had never been arrested in relation to, or charged with, any offence.
But sources yesterday said the 22-year-old man had been seen with criminals who were associated with a major drug dealer in the Clondalkin area.
“He’s been seen in the company of people involved in drugs, people who are associated with a major dealer,” said one source.
“Some of these people don’t need many reasons to kill a young fella.”
They are now tracing the movements of local criminals, including drug dealers known to the victim.
Detectives stressed this was just one line of inquiry and that they were also investigating the possibility the murder stemmed from a personal row.
The shooting dead of Mr Dowdall, the first so-called gangland murder of the year, was witnessed by his girlfriend, Ms Debbie Quinn, 21. Shortly after 10pm, Ms Quinn answered a knock to her door. Two masked men pushed past her and singled out Mr Dowdall in the sitting-room.
As Ms Quinn pleaded with the assailants, one of them fired a number of shots, believed to be from a shotgun, at close range into the victim. The gunmen then fled on foot.
The couple had only moved into their first home together, a three-bedroom house, just before Christmas and were planning a life together.
Ms Quinn was described as being “inconsolable” and was being cared for by Mr Dowdall’s family, including parents Damien snr and Carol, who live nearby.
A devastated Ms Carol Dowdall said: “He was loved by everyone, not an enemy, obviously he had one, but not an enemy in the world. He had friends everywhere.”
Damien snr said his son was not in any trouble and had not been involved in any criminality.
A senior garda said: “He had never been before the courts, he wasn’t a witness to any case, he was not suspected of giving information to gardaí. It’s very puzzling, especially given the level of brutality.”
Detectives said they would investigate the link with a major drug dealer, who is currently facing serious charges. He is charged with connection with an offence involving a friend of Mr Dowdall.
But sources said that Mr Dowdall was not a witness in the case and that they did not know of any row between the deceased and the drug dealer.
“We will be tracing the movements of people involved in criminal activity, including the people who had been seen with the deceased,” said a source.
Gardaí will liaise with the victim’s family and his girlfriend to see if they know of anyone who might have had a grudge against him.
Meanwhile, gardaí in south Dublin arrested two men after shots were fired into a house in Loughlinstown yesterday.