Two people have been released on bail following a fire at a flat in Long Eaton at the weekend.
Police were called to reports of a fire on Saturday on Lynden Avenue at 5.40am.
Police, fire service and the ambulance service all attended and a 51-year-old man was taken to hospital with burn injuries. He later died in hospital.
A 54-year-old woman and a 51-year-old man were arrested in connection with the alleged incident, on Saturday afternoon, and remained in police custody until yesterday evening.
DI Steve Shaw, who is leading the investigation, said: “Although we initially launched a murder investigation, in relation to the case, we always keep an open mind as to the circumstances surrounding such incidents.
“Our detectives will continue to work on this very complex investigation and we will issue further updates as they become available.”
Anyone who was in the area at the time and noticed anything suspicious, or who has CCTV installed nearby, is asked to call police on 101 quoting reference number 19*328726.