Detectives probing the murder of a prison officer in Northern Ireland are questioning three men over the killing, including one arrested in the Irish Republic.
David Black, 52, was gunned down on Thursday during a high-speed ambush on a motorway as he drove to work at Maghaberry high-security prison.
His funeral will take place on Tuesday at Molesworth Presbyterian Church in Cookstown, Northern Ireland, where the father-of-two had attended regularly.
Two men, including prominent dissident republican Colin Duffy, were arrested north of the border on Friday morning before a 29-year-old suspect was detained in the Irish Republic on Friday night. They remain in police custody in connection with the murder.
Duffy, 44, was detained with a second man in Lurgan, Co Armagh, just miles from where Mr Black was ambushed on the M1 motorway on his way to work at the top-security prison, near Lisburn, Co Antrim. The 29-year-old suspect was detained in Co Leitrim and taken to Carrick-On-Shannon garda station under Section 30 Offences Against the State Act 1939.
Mr Black's killing has prompted condemnation from across Britain and Ireland while detectives leading the inquiry insisted they needed the public's help to bring the killers to justice.
Superintendent Keith Agnew declared: "Condemnation, however strident, is not enough. It needs to be translated into information if our investigation is to make maximum progress."
Duffy, who has been cleared of murder charges on three separate previous occasions - the latest last January after two soldiers were shot dead outside Massereene Army barracks in March 2009 - was arrested at his home in the Kilwilkie estate where republicans opposed to the peace process have huge support.
Politicians on all sides condemned the murder of the prison officer, who was planning to retire next year after more than 30 years of service.
Taoiseach Enda Kenny, who was in Armagh for talks with Northern Ireland First Minister Peter Robinson and Deputy First Minister Martin McGuinness, said the dissident republicans had been linked to criminality and drug dealing which had also led to deaths on the streets of Dublin. Mr Black's murder had overshadowed the meeting, he said.