Three people were arrested this morning.
A mother and son are being questioned in connection with the abduction and torture of Kevin Lunney.
They were arrested earlier this morning along with another man, following the attack on the Quinn Industrial Holdings director two months ago.
The two men, 20s and 40s, can be held for questioning for up to a week.
Meanwhile the woman, who is in her 50s, can be detained for up to three days.
The arrests are one the most significant developments in the investigation into the attack on Kevin Lunney to date.
Mr. Lunney was found on the roadside in Cavan on the 17th of September after he was abducted outside his Fermanagh home.
The 50-year-old father of six was slashed with a knife, doused with bleach and branded by his attackers.
Directors at Quinn Industrial Holdings have been subjected to a five-year campaign of intimidation.
Justice Minister Charlie Flanagan has rejected claims that Gardaí have been turning a blindeye to conflict in border areas in recent years.
There has been criticism of the Garda response to the intimidation before the abduction and torture of Mr. Lunney.
