A third person has been arrested in connection with the fatal shooting of Edward O'Connor in Finglas in Dublin on Sunday afternoon.
The 22-year-old man is being held at Blanchardstown Garda Station.
A man, aged in his 20s, and a woman, aged in her 30s, who were arrested last night, are still being questioned in connection with the murder of the 41-year-old grandfather.
Mr O'Connor, from Barn Lodge in Finglas, died after he was shot several times on the Ballycoolin Road in Finglas.
He was shot just after 5pm yesterday and was taken to Connolly Hospital in Blanchardstown, where he was pronounced dead a short time later.
Gardaí believe the murder is connected to a fight in a pub during which a relative of the victim was seriously injured.
Groups from opposing sides in that dispute are thought to have arranged to meet for a fight at the Ballycoolin Road yesterday evening, but a gun was produced and Mr O'Connor was shot.
Detectives are now trying to identify and interview everyone who was at the scene at the time.
The scene of the shooting remains sealed-off.
The Ballycoolin Road from the Premier Business Park to the Cappagh Road is closed to traffic.