Investigations are continuing after a suspected gang member from Northern Ireland died following a police raid in Buxton.
Derbyshire Constabulary officers carried out a search warrant at a property on Rockfield Road, Fairfield, last Friday on behalf of the Police Service of Northern Ireland.
A force spokesperson said: "Shortly after that warrant was carried out at 7.30am, a man inside the property was taken ill.
"Despite first aid being administered by our officers, the 54-year-old man was later pronounced dead."
The spokesperson added: "We have referred ourselves to the Independent Office of Police Conduct (IOPC), which has now launched an investigation into the circumstances.
"As a result, we are unable to make any further comment."
A spokesperson for the IOPC said on Thursday: "Our investigation has gathered body worn video footage, initial accounts from police officers who were present and police radio transmissions.
"From our early enquiries there is no evidence that Taser was deployed during the incident but work is still ongoing to confirm this.
"A post-mortem examination was carried out on Monday and the cause of death has yet to be established.
"The results of further tests are awaited.
"We are liaising with the family of Mr McGuinness and we will continue to keep them informed as our work progresses.
"We have verified that Derbyshire police officers were executing a warrant at the property when Mr McGuinness became unwell.
"He was taken to a hospital where he was sadly pronounced dead that morning."
Mr McGuinness's inquest is due to open at Chesterfield coroners' court on Monday.
According to our sister title Belfast News Letter, the person who died was Cyril McGuinness, also known as 'Dublin Jimmy' - one of the men suspected of the abduction, assault and torture of a Northern Ireland businessman called Kevin Lunney.
It is understood Mr McGuinness, originally from the Derrylin area, was being treated as a chief suspect in the investigation into Mr Lunney's abduction.
It is thought Mr McGuinness, who was well-known to the authorities on both sides of the border, was 'lying low' in England amid the intense public and police focus on the crime.
Mr Lunney, a director of Quinn Industrial Holdings (QIH) in County Fermanagh, was abducted close to his home in September.
The gang took Mr Lunney across the border where they viciously assaulted him, breaking one of his legs, slicing his face with a blade and carving the letters QIH on his chest before pouring bleach over him.
The attack came amid five years of co-ordinated intimidation of businesses which own companies formerly run by Irish business tycoon, Sean Quinn.
The Quinn family has consistently condemned and distanced themselves from those attacking the new owners.
Detective Chief Inspector, of the Police Service of Northern Ireland, said: "The investigation is continuing at pace.
"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."