A third man has been arrested in connection with murder of 34-year-old Quham Babatunde on South Anne Street in Dublin at the weekend.
The man, who is in his 20s, is being detained under section 4 of the criminal justice act and can be questioned for 24 hours.
Two people were previously arrested - one in Belfast and one in Dublin - in connection with the fatal stabbing of the 34-year-old.
A man was arrested by the PSNI in Belfast as he was about to board a ferry to Liverpool.
Gardaí investigating the murder had contacted the PSNI as part of their investigation.
A second person was arrested following a number of searches in Dublin this morning.
The man, aged in his 20s, was detained in Balbriggan and is being held at Pearse Street Garda Station.
Mr Babatunde died after he was stabbed on South Anne Street in the early hours of Saturday morning.
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It is understood an incident occurred following a row between two groups of people out socialising.
Gardaí were alerted to the incident shortly after 3am and Mr Babatunde was found unresponsive and with serious injuries.
He was treated at the scene before being taken to St James's Hospital, where he was later pronounced dead.
A post-mortem examination has been completed on Mr Babatunde's body, the results of which are not being released for operational reasons, gardaí have said.
A second man, aged in his 30s, who was injured in the same incident, was treated for non-life threatening injuries in hospital. He has since been discharged.
