Four members of the same family have been arrested in the cross-border investigation into the campaign of violence against the directors of Quinn Industrial Holdings (QIH).
This is the second series of arrests in the probe involving gardai and the PSNI since the abduction and torture of QIH director Kevin Lunney last September.
The Herald understands three members of the same family were arrested by the PSNI in Co Fermanagh, while a fourth was arrested by gardai in Co Cavan.
Two men aged 23 and 61 and a woman aged 61 were arrested on suspicion of conspiracy to kidnap and conspiracy to cause grievous bodily harm with intent and assisting offenders.
They were taken into custody at Omagh PSNI Station for questioning.
In Cavan, gardai arrested a man in his 30s. He was detained at Cavan Garda Station.
The operation marks a new phase in the investigation, as gardai have made "major progress" and succeeded in un- covering the money trail used by the late border gang boss Cyril McGuinness.
The senior criminal was nicknamed Dublin Jimmy and died last November during a police raid in England.
It was recently revealed that the discovery of a number of bank accounts used by bogus front companies set up in the Republic on behalf of McGuinness may lead directly to the mysterious kingpin who paid him to orchestrate the campaign of violence.
The arrests also come in the wake of an attempted arson attack at the home of a relative of one of the QIH directors in Co Fermanagh last month, when two men tried to set fire to a nearby truck and an SUV.
However, the would-be arsonists were disturbed and sped off before any damage was done, and the incident was captured on CCTV.
Security chiefs fear the incident marked a resumption of the violence against the QIH executives, which had ceased following the abduction and torture of Mr Lunney.
There had been quiet opti- mism that the campaign of intimidation would end permanently following McGuinness' death.
In January, gardai informed the five directors of QIH who have been targeted, including Mr Lunney, that the threat level against each of them is "as high as it has ever been".
Chief Superintendent John O Reilly, of Cavan/Monaghan Garda Division, said yesterday: "Today's arrests demonstrate An Garda Siochana's ongoing commitment, working closely with the PSNI, and is a further significant step to ensuring that the perpetrators of this vicious attack will be brought to justice."