The main suspect in the investigation into the kidnap and torture of a Northern Irish businessman has died during a police raid in Derbyshire.
Cyril McGuinness, 54, became ill as police searched his home in Buxton on Friday morning.
That search was part of a joint police operation across the UK and Ireland in which almost 20 properties were raided.
Quinn Industrial Holdings executive Kevin Lunney was beaten and tortured by three men in an attack on 17 September.
Police say the raids at home and businesses in Derrylin in NI, Cavan, Longford and Dublin in the Republic of Ireland and Derbyshire were “significant”.
McGuinness had been a target of the police on both sides of the Irish border for years and had more than 50 previous convictions.
By Julian O’Neill BBC News NI Home Affairs Correspondent
Police on both sides of the border are under pressure to get results, following a long-running series of threats and other incidents.
The campaign against Quinn Industrial Holdings and senior staff has spanned several years.
There have been scores of incidents, but to date no individuals have been charged.
The abduction of Kevin Lunney represented a significant ratcheting up of things.
Police in the border region have given priority to the investigation and the scale of the co-ordinated searches appears to represent a major response.
He was the main suspect in the kidnapping and extremely violent attack on 50-year-old Mr Lunney, who was abducted as he was driving home from work in Kinawley, County Fermanagh.
The father-of-six had his leg broken, was slashed with a knife and doused with bleach in a two-and-a-half hour ordeal.
He had the letters “QIH” cut into his chest with a Stanley knife, and told BBC NI’s Spotlight programme this week that he feared that he would never see his wife and children again.
After the attack, Mr Lunney was dumped by a road in County Cavan, 22 miles (35km) away, where he was found by a member of the public.
As part of the latest police operation, PSNI are undertaking five searches in Derrylin, County Fermanagh, while in England police in Derbyshire are also conducting a search operation.
Gardai (Irish police) said 100 officers were involved in searching five locations in County Cavan, three in County Longford and four in Dublin.
They said these are a mixture of domestic dwellings and commercial/business premises.
PSNI Dt Ch Insp Julie Mullan said: “This was a truly horrific crime and we continue to work closely with our colleagues in An Garda Siochana and now also Derbyshire Constabulary to try and bring the perpetrators to justice.”
In the past week, signs near the headquarters of QIH in Derrylin, County Fermanagh, attacking the directors have been removed and the Police Service of Northern Ireland has increased patrols and checkpoints in the area.
Meanwhile, the directors of Quinn Industrial Holdings have rejected an offer to meet members of the Quinn family, the Irish News has reported.
It said Sean Quinn junior had made the offer in a statement to BBC Spotlight NI.
In 2014, the companies comprising Quinn Industrial Holdings (QIH) were bought over by six businessmen including former associates of his father Sean Quinn.
Mr Lunney, who had worked with Sean Quinn for many years and remained loyal to him after he lost control of the empire, was reinstated as a director and Mr Quinn was employed as a consultant.
But Mr Quinn left this role in 2016 and later said he was forced out and his family had been “stabbed in the back”.