Three Leicestershire police officers and four police staff are being investigated after a man arrested on suspicion of kidnap and murder was found dead in his cell. Sebastian Zarnoch, 30, was initially arrested on 3 September in connection with the kidnapping of a missing woman, Gabriela Kosilko, and was detained at Keyham Lane police station. The next day he was further arrested for the murder of Kosilko, 26. He was found unresponsive in his cell shortly after 10am on 6 September and his death was pronounced there a short time later, the Independent Office for Police Conduct (IOPC) said. The IOPC has now told the seven police officers and staff they are under criminal investigation for the possible offence of misconduct in public office. The three police officers have also been served with gross misconduct notices for potential breaches of police standards for professional behaviour. Four staff members have been advised they are to be made subject to a disciplinary investigation. The conduct notices relate to the level of risk assessments and supervision involving 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 did not necessarily mean that criminal charges or disciplinary proceedings would follow. After Leicestershire police informed the IOPC of Zarnoch’s death, the watchdog sent investigators to the police station to begin gathering evidence including custody footage and some initial accounts from officers and staff. It declared an independent investigation the same day. A postmortem examination was held on 11 September and the results of further tests are awaited. The 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.” Kosilko was last seen at a shop in Fosse Road North, Leicester, at about 11.30pm on Thursday 31 August. Her car, a red Audi A1, was found in Ratby Lane, Leicester, at 4.20pm the next day and she was reported missing. Her body was found in woodland near Groby Pool, outside Leicester, on 6 September.