A 43-year-old man’s finger was severed while he was being detained by Derbyshire police.
The Independent Police Complaints Commission, or IPCC, is investigating the incident, which took place in Dronfield on Saturday, June 6.
It said the man was arrested and placed in a caged area in the back of a police van, which was then driven to Chesterfield police station.
The IPCC said when officers arrived at the station and attempted to remove the man from the caged area, they realised his left hand was bleeding and his little finger had been severed.
The man’s finger was recovered and he was taken to hospital for treatment.
An IPCC sppkesman said: “Unfortunately, his finger could not be reattached.
“The IPCC investigation is looking at the circumstances surrounding police contact with the man, including his arrest and the appropriateness of force used.
“Investigators are also examining how the man was placed in the rear of the police van, whether any observations were carried out while in police transit and whether any medical treatment was provided before being taken to hospital.”
Anyone who may have witnessed the man being placed in the police van at around 11.40pm near the Green Dragon pub in Church Street is asked to contact the IPCC on 0800 151 0020 or email email@example.com.
This is the second IPCC probe for Derbyshire Constabulary to be announced this month after the watchdog opened an independent investigation into the death of a man in police custody in Chesterfield.
Paul Jones, 37, from Belper, was taken into custody on Friday, June 26 and taken to Chesterfield police station.
After becoming unwell, he was transferred to hospital, where he died.
An inquest at Chesterfield coroners’ court was opened and adjourned on Tuesday, July 7.