Sebastian Zarnoch, 30, was initially arrested on September 3 in connection with the kidnapping of missing beautician Gabriela Kosilko, 26, and was detained at Keyham Lane police station. He was further arrested the day after for her murder.
Mr Zarnoch was found unresponsive in his cell shortly after 10am on September 6 and was pronounced dead there a short time later, the Independent Office for Police Conduct (IOPC) said.
Seven people working for Leicestershire Police have now been told by the IOPC that they are under criminal investigation for the possible offence of misconduct in public office.
Three are police officers who have also been served with gross misconduct notices for potential breaches of police standards for professional behaviour. Four are staff members who are to be made subject to a disciplinary investigation.
The conduct notices relate to the level of risk assessments and supervision involving Mr Zarnoch and whether the observations and cell checks carried out on him were in line with relevant policy and procedure.
The police watchdog said the serving of notices does not necessarily mean that criminal charges or disciplinary proceedings will follow.
After the IOPC were informed of Mr Zarnoch’s death by Leicestershire Police, they sent investigators to the police station to begin gathering evidence including custody footage and some initial accounts from officers and staff.
They declared an independent investigation the same day.
Awaiting post-mortem examination report
A post-mortem examination was held on September 11 and the results of further tests are awaited.
IOPC regional director for the West Midlands Derrick Campbell said: ‘Whenever someone dies while in police custody it is important that all of the circumstances are independently investigated. We have been in contact with Mr Zarnoch’s family to express our sympathy and explain our role.
‘Following the conclusion of our investigation, we will decide whether to refer the matter to the Crown Prosecution Service for a charging decision and we will determine whether any officer should face disciplinary proceedings.’