Two men have been arrested as part of the investigation into the torture and abduction of Kevin Lunney.
The Quinn Industrial Holdings Director suffered life changing injuries when he was taken near his home in Fermanagh and violently assaulted in September.
Two men, both aged 38, are being held at Ballymun and Finglas Garda stations. The pair are being held under Section 50 Criminal Justice Act 2007.
They are the fifth arrests to be made as part of the case.
Two men and a woman were arrested last week. They were later released without charge.
In a statement Gardaí have again appealed for information;
"no matter how insignificant it appears, on this vicious criminal attack or any other criminal activities which have taken place in the Cavan/Fermanagh border area over recent years"