Five police officers will face a misconduct hearing after a man lost the tips of three fingers when they were trapped under a toilet rim.
Essex Police officers entered the 33-year-old arrested man's cell on 1 May 2015 to remove his foot from a toilet.
The police watchdog said "a number of techniques" were used to remove him, but he grabbed on to the rim and his fingertips were severed as officers tried to restrain him.
The hearings are set to begin on 7 May.
An investigation was launched by the Independent Office for Police Conduct (IOPC) after the injuries to the man's left hand at Colchester Police Station.
The watchdog said it looked at the decision making by officers "when the man, who was a foreign national presenting mental health concerns, was booked in to custody" and "in relation to the techniques and force used to remove the man from the toilet".
It also investigated the first aid the man received and his "continued detention" after his return from hospital.
As a result, an inspector, three police constables and a temporary police sergeant are due to face gross misconduct charges.
The IOPC said a police sergeant had already admitted misconduct, while another officer received "management action".
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Essex Police has since replaced toilets of a similar design involved in the incident.
The IOPC said its final report was sent to the Crown Prosecution Service, which decided in August no criminal charges would be brought.