The RUC has arrested another two people in connection with the killing early on Saturday of a Catholic student, Mr Ciaran Heffron (22), in the Co Antrim village of Crumlin.
This brings to four the number being questioned by police over the murder. Two men were arrested within hours of the attack.
No group has admitted killing Mr Heffron, but the Loyalist Volunteer Force (LVF) is being blamed. There has been no statement of admission for a number of recent attacks believed to have been carried out by the LVF, including the murder of Mr Adrian Lamph (29) in Portadown last Tuesday.
Mr Heffron was shot dead as he walked home from a night out with friends in a pub in Crumlin between 2 a.m. and 3 a.m. on Saturday.
He was a student at the University of Ulster in Coleraine, and a minute's silence will be observed in the university today as his funeral takes place.
In Portadown, the RUC has arrested three people in an early-morning operation. The three, believed to be two men and a woman, are being questioned at Gough barracks, Armagh, in relation to the murder of Mr Lamph.
Mr Lamph, a council worker with Craigavon Borough Council, was shot dead by a lone gunman in Portadown.