The Independent Police Complaints Commission (IPCC) is appealing for information, to assist its investigation into the death of a Polish man who died in hospital after being detained by police last month.
The watchdog is asking for people who knew Rafal Delezuch while he lived in Leicester, as well as anyone who witnessed events around the time he was detained on Wednesday 15 August 2012.
Mr Delezuch, who was 26, was known to attend the Anchor Centre on Dover Street. He had previously lived at an address in Mere Road. He is believed to have come to the Leicester area around two years ago.
A post-mortem examination was inconclusive and further tests are being carried out.
Police were called to Devana Road in Highfields on 15 August to reports of a man acting strangely in the street. Mr Delezuch was detained under Section 136 of the Mental Health Act. During the detention, police used incapacitant spray and restraints.
Mr Delezuch was taken by police van directly to the Leicester Royal Infirmary, due to concerns for his welfare. He died in hospital at around 12.30pm.