A man in his 30s arrested in connection with the abduction and assault of Kevin Lunney, has been released without charge.
On Thursday, gardaí arrested the man and detained him at Cavan Garda station.
A file will now be prepared for the Director of Public Prosecutions and investigations are continuing.
Mr Lunney, a director at Quinn Industrial Holdings (QIH), was abducted outside his home near Derrylin, Co Fermanagh, last September and taken to a horsebox across the border, where he was savagely beaten.
His attackers broke his leg, sliced his fingernails and face with a Stanley knife, carved QIH on his chest, and doused the father of six in bleach.
The attack was the most serious in a five-year campaign of intimidation targeting the companies and directors that now control the business portfolio which was built up by fallen tycoon Sean Quinn, once Ireland’s richest man.