Gardai were last night interviewing a man in his 20s about the murder of the INLA member, Mr Patrick Campbell, during a fracas in the west of the city two weeks ago.
The man, one of two brothers from the Crumlin area who left Dublin and went to London in the aftermath of the incident, was arrested early yesterday on Crumlin Road.
It is understood he and his brother returned to Dublin after running out of money.
Yesterday he was being questioned by detectives investigating the murder of Mr Campbell (22) who was part of an INLA gang involved in the fracas with members of a west Dublin drugs gang. Mr Campbell died from blood loss and head injuries after he was attacked by men armed with a machete and nail-studded clubs.
The INLA warned that it would carry out killings in retaliation for his death.