Four men were arrested today over the gangland murder of a criminal in February.
Aidan Byrne was shot dead in a car off the North Circular Road in Dublin after being lured to the area.
The arrested men, three in their 20s and one in his 30s, were arrested in the capital today.
They were taken to the Bridewell, Pearse Street, Store Street and Mountjoy Garda Stations for questioning under Section 50 of the Criminal Justice Act 2007.
Byrne was believed to have been aligned to one of the factions involved in a bloody feud in the north inner city.