A nest of dissident republicans - including some former Real IRA members - is under investigation for playing a key logistical role in the kidnap and torture of Quinn Industrial Holdings senior executive Kevin Lunney.
Members of the group have been associated in the past with Cyril McGuinness, the alleged gang leader, who died after Derbyshire police raided his "safe" house in Buxton in the English East Midlands on Friday.
The dissidents are located in the Derrylin and nearby areas of Co Fermanagh and some have links in Co Cavan.
They are suspected of being recruited by McGuinness to provide backup support for the kidnap gang and some of them may have been part of the group who took part in the abduction, along with Dublin criminals.
One of the vehicles used by the gang was stolen in Dublin while another was sourced in the border area.
Officers in the joint Garda-PSNI investigation believe eight to 10 people were involved in the abduction, although this number may grow when the forensic examination of documentation, laptops and mobile phones seized - during the raids in counties Cavan, Dublin, Longford and Fermanagh as well as McGuinness' bolt-hole - has been completed.
Investigators are satisfied that the seized items will produce significant material that will progress their inquiries significantly but the full extent of what is available will not be clear for another few days.
The main spotlight is on the potential evidence gleaned from the house in Buxton where McGuinness believed he was secure and could not be traced.
More than 100 officers were involved in the searches on Friday. Gardai provided key intelligence which resulted in the raid by Derbyshire police on his hideout.
McGuinness became ill during the raid at 7.30am.
He collapsed and later died in hospital.
He is thought to have suffered a heart attack after Derbyshire police officers, who were acting at the request of the police forces here, burst in through his front door.
Houses used by McGuinness had been raided by police 15 times over the past two decades, although none produced incriminating evidence against him.
But the investigation team this time is more than hopeful that the documents and electronic devices seized on Friday morning will yield vital clues that will lead them to others involved in the horrific crime and, possibly, the person known as the 'paymaster'.
Mr Lunney (50), a father of six, was abducted from his Co Fermanagh home before being brought to a container in Cavan where he was beaten, sliced and had bleached poured over him in an ordeal lasting over two hours.
Meanwhile, gardai have dismissed claims by Irish junior minister Michael D'Arcy that Quinn Industrial Holdings (QIH) executives had been let down by their personnel based along the border. They pointed out that all previous attacks and incidents involving QIH executives in the Republic had been investigated and files prepared for the Director of Public Prosecutions.
But none, bar one, produced sufficient evidence to sustain a criminal charge.
Reviews of those files have been carried out by other officers to ensure that nothing important was missed in the initial inquiries.
Gardai are also furious at suggestions that they ignored intimidatory signs that had been erected on both sides of the Cavan-Fermanagh border.
They said some of the signs had been put up on private property and required a warrant to remove them, while others that had been put on display on publicly owned land had been removed but replaced in the following days.