Three people arrested by Police Service of Northern Ireland (PSNI) detectives investigating the kidnap and torture of Co Fermanagh businessman Kevin Lunney have been released unconditionally.
The two men, aged 23 and 61, and one woman aged 61 were detained in the Fermanagh area on Thursday on suspicion of conspiracy to kidnap, conspiracy to cause grievous bodily harm with intent, and assisting offenders.
The Police Service of Northern Ireland (PSNI) announced their release from custody in Omagh police station on Friday.
In the Republic on Thursday, the Garda arrested a man in his 30s in relation to the abduction and assault. He was detained at Cavan Garda station. Gardaí said he remained in custody on Friday.
Mr Lunney, a director at Quinn Industrial Holdings (QIH), was abducted outside his home near Derrylin, Co Fermanagh last September and later assaulted and tortured.
For almost a decade executives and companies involved in the management or acquisition of assets formerly owned by former billionaire Sean Quinn have been subjected to a campaign of violence. Mr Quinn has condemned the violence and has said that those carrying it out were not acting in his name.
The Garda and PSNI established a joint investigation team to work on the case last November.
A serial criminal considered a key suspect in the kidnapping and torture died from a heart attack when police arrested him in Buxton, Derbyshire, last November.
Cyril McGuinness, known as Dublin Jimmy, was believed to have been hiding out in the area following the assault.
In December, four men were remanded in custody at a court in Co Cavan charged with the kidnap and torture of Mr Lunney.–Additional reporting: PA