Gardaí, as part of a joint Garda and PSNI operation investigating the murder of prison officer David Black, have arrested two men in Co. Donegal.
Mr Black, 52, was shot dead by dissident republicans as he drove along the M1 on his way to work at Maghaberry Prison in November 2012.
They have detained a man in his 40s under a European Arrest Warrant and a second man in his late 50s under Section 30 of the Offences Against the State Act, 1939.
Last month, a European Arrest Warrant was obtained for Damien Joseph McLaughlin, aged 40, from Co Tyrone, who was due to stand trial in February on charges that include aiding and abetting his murder but fled while on bail.
McLaughlin had initially been fitted with an electronic tag while on bail but he was permitted by a court to remove it in December 2014 despite strong police objections.
The man in his 40s is due to appear before the High Court in Dublin on foot of a European Arrest warrant tomorrow morning
One man is being held at Letterkenny Garda Station and the other at a Garda Station in Dublin.
Detective Chief Superintendent Raymond Murray, from PSNI's Serious Crime Branch, said: "Since his disappearance police have carried out extensive enquiries regarding Mr McLaughlin's whereabouts.
"Throughout this time the PSNI has been liaising closely with An Garda Siochana and (the) arrest demonstrate the benefits of joint working between police forces and other national partner agencies."
Mr Murray added: "Damien McLaughlin is scheduled to appear at Dublin's Central Criminal Court tomorrow."