A man arrested in connection with the assault and abduction of Quinn Industrial Holdings director Kevin Lunney has been released without charge.
The man, aged in his 30s, was one of four people arrested on both sides of the border on Thursday.
Mr Lunney was kidnapped and brutally assaulted by a group of masked men last September.
The attack was the most serious act in a campaign of intimidation against executives at QIH that has been ongoing for several years.
On Thursday, police arrested two men – aged 23 and 61-years-old – and one woman - aged 61 - in the Fermanagh area.
Separately, Gardaí arrested a man in his 30s in the Cavan area.
Police in the North released the three people without charge yesterday.
This morning, Gardaí released the fourth person without charge.
Gardaí said a file will now be prepared for the Director of Public Prosecutions.