GARDAI are tracking down a group who had been socialising with prolific burglar Christopher Warren shortly before he was murdered.
Officers hope the men will be able to supply key information that could help identify his killers.
Warren died shortly after he was shot in what appeared to have been a punishment attack that went wrong.
Two men have already been questioned and more arrests are expected in the coming days.
Warren is known to have been drinking with friends in the Cork Street area of Dublin's south inner city earlier that Friday and some of those have since been contacted by investigating gardai.
Officers hope to locate the rest of them over the next week.
They believe the shooting was linked to an incident at a premises in Inchicore, in south west Dublin, on St Stephen's night.
Warren (35), from St Teresa's Gardens, is alleged to have struck a woman in a premises in a row that apparently erupted over drugs.
A number of men are understood to have plotted to abduct Warren and punish him in revenge for the earlier incident.
It is not yet clear whether they had intended to shoot him in the legs or physically assault him.
But Warren either spotted the gun while he was in a car with his attackers and tried to make his escape or else struggled with the men.
He was shot in the upper body and also in the lower leg. Gardai are satisfied that the shooting took place at Constitution Hill in the north inner city.
A friend of the victim was in the area and collected Warren to take him to St James's hospital.
Warren was left outside the hospital's accident and emergency unit and was rushed inside for medical treatment but died shortly afterwards.
In the meantime, gardai were alerted and found the car used by his friend abandoned in the Cork Street area.
The blood-stained vehicle has since been forensically examined by members of the garda technical bureau.
Gardai have also established that Warren was shot with a handgun and have carried out searches to locate the weapon.
Warren had been granted temporary release from prison for Christmas.