A man in his 20s has been arrested in connection with the murder of David Byrne at the Regency Hotel in Dublin last February.
The man is being held under anti-gang legislation at Ballymun Garda Station and can be held for up to seven days.
It is the first arrest in the investigation into the killing.
The man was detained at around 8pm along with a second man in his 20s who was arrested on suspicion of dangerous driving.
Mr Byrne, 33, was shot dead at a boxing weigh-in by an armed gang as part of a feud between two criminal gangs.
