A police officer is being investigated for alleged assault after an 80-year-old man became seriously unwell in custody.
The Independent Office for Police Conduct (IOPC) said it was looking into the circumstances surrounding the incident, involving a Cheshire Police officer in Runcorn.
The watchdog said the man had been arrested for suspected drink driving shortly after 23:30 BST on 7 December and arrived in custody in the early hours of the following morning.
At 06:00 staff reported the man was having a seizure and he was taken to hospital, where it was discovered he had had a stroke.
The IOPC said it was unclear whether that happened before or after he was arrested, but its investigation had identified concerns about the use of force during a cell check at 04:30.
The watchdog said a police officer had been informed they were under investigation for assault, as well as potential gross misconduct.
“In light of the seriousness of the man’s condition, it is important for the circumstances of his arrest and detention to be independently investigated,” IOPC director Amanda Rowe said.
“While it is not clear whether the police use of force may have contributed to the man’s condition deteriorating, evidence gathered so far indicates a criminal offence may have been committed.
“On conclusion of our investigation, we will decide whether to refer the case to Crown Prosecution Service or whether misconduct proceedings are appropriate.”
