The main suspect in the investigation into the abduction of Kevin Lunney has died.

Cyril McGuinness, who was in his 50s, took ill when Derbyshire police searched his home in the Buxton area of the UK this morning.

McGuinness, a convicted criminal and was originally from Swords, Co Dublin, went by the nickname 'Dublin Jimmy'.

Gardaí and the PSNI believe he was the main organiser behind the kidnapping and extremely violent attack on the Quinn Industrial Holdings executive in September.

McGuinness has been a target of the police on both sides of the border for years and has more than 50 previous convictions.

Searches were carried out on both sides of the border, as well as the search in Derbyshire as part of the investigation of the abduction of Quinn Industrial Holdings executive.

More than 100 gardaí are involved in searches of properties in Cavan, Longford and Dublin.

PSNI officers carried out five searches in Derrylin, Co Fermanagh, while police in Derbyshire conducted a search operation in England.

Houses and business premises were searched in five locations in Co Cavan, three locations in Co Longford and four in Dublin.

Gardaí said the searches are part of "the evidence gathering stage to progress the investigations" into the abduction, false imprisonment and assault of Mr Lunney on 17 September in the border area.

The 50-year-old father-of-six was found bleeding on a remote roadside after being abducted outside his home in Derrylin and later dumped in Co Cavan.

PSNI Detective Chief Inspector Julie Mullan said: "This was a truly horrific crime and we continue to work closely with our colleagues in An Garda Síochána and now also Derbyshire Constabulary to try and bring the perpetrators to justice."

Earlier this week, Mr Lunney recounted in a BBC interview how he was slashed with a knife, doused with bleach and branded by his captors.

Commissioner Drew Harris and Assistant Chief Constable Mark Hamilton PSNI at a press briefing into the investigation into the abduction of Kevin Lunney at Garda Headquarters today pic.twitter.com/YDGzrrbgA5 — Garda Info (@gardainfo) November 8, 2019

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Garda Commissioner Drew Harris appeared alongside PSNI Assistant Chief Constable Mark Hamilton at a press conference at Garda Headquarters to announce a new cross-border Joint Investigation Team.

Mr Harris said the announcement and the searches happened today by "coincidence".

When asked about the death of the man in England, he said: "That is our understanding, but that matter happened within a search in England and that is being pursued by the authorities there."

Mr Hamilton described the death as "regrettable".

"The PSNI commissioned a search in England with the support of the police officers there and a report has been that a man has died, which is very regrettable," he said.

"That is now a matter of investigation in England separate to this ongoing inquiry."

Mr Hamilton declined to be drawn when asked whether the dead man was a main suspect in the investigation.

The new Joint Investigation Team will be overseen by EU law and order agency Eurojust.

It will allow officers on both sides of the order to investigate the attack on Mr Lunney and all attacks on QIH executives dating back to 2012.

Mr Harris described the agreement as an "important advance" and said gardaí were committed to keeping the people of Co Cavan safe.

"These are well resourced investigations, they are proceeding, they are making progress," he said.

"At the same time we have made a commitment to the policing of Co Cavan and to assure the people of Co Cavan that the rule of law will prevail.

"These (attacks) have been obviously a subject of public concern lately and we want to be seen to act in a strong and robust way to show that there's no room for criminality anywhere on the island of Ireland and that as police services we are cooperating in the strongest fashion possible to bring the perpetrators to justice."

Asked if the joint investigation would be targeting the "paymaster" behind the intimidation campaign, Mr Hamilton urged "patience".

He said today's searches represented "one phase" of the probe and there would be "other phases to come".

Mr Hamilton added: "We have made a significant effort to try to make sure the people of Fermanagh feel safe during this period and we are working very collaboratively on both sides of the border to do that.

"Hopefully it reinforces to the community and to the criminals that we are determined that they will have no hiding place on the island, north or south."

In a statement, Quinn Industrial Holdings said it welcomed searches by gardaí, the PSNI and Derbyshire Constabulary.

QIH said the operation marked an "important milestone in bringing those involved in attacks on QIH staff to justice".

The company urged anyone with information to contact the gardaí or the PSNI.

A former Assistant Chief Constable in the RUC and PSNI has described Cyril McGuinness as "really heavyweight organised criminal in Fermanagh/SouthTyrone."

Speaking on RTE's Drivetime, Alan McQuillan said McGuinness would have had associations with the IRA, but that "his main interest was money."

Mr McQuillan said McGuinness was a criminal entrepreneur and that the key questions is "who is paying the money?"

He said he did not believe a cross-border agency was required at this stage, because he said it would take a long time to set up, adding "we have an immediate problem" in relation to QIH.

Mr McQuillan added that the other potential crimes taking place in the area are of a "relatively low level".