Police say they have found no rational explanation for the death of Naazish Farooq Khan from Bradford, West Yorkshire.
She was suffering from lymphatic cancer and appeared to have died of natural causes on 8 October at St James' University Hospital, Leeds. Her body was exhumed last Wednesday after tests on samples taken while she was an in-patient.
Her body was taken from a cemetery in Bradford to Sheffield, where a post mortem examination was carried out. Tests are being carried out. The results will not be known for several weeks.
West Yorkshire Police said the decision to exhume her body was taken following advice from forensic experts.
Naazish's father, Mohammed Farooq Khan, an electronics engineer, broke down as he revealed at a press conference how his eight-year-old daughter, Shabana, had died of the rare Epstein Bar virus. It is present in hepatitis and lymph cancers. Police are not investigating her death.
Mr Khan said of Naazish's death: "We were not interested in the medication. We were just focussing on her well-being. Having been through it before with our other daughter we were not interested in anything other than Naazish's well-being." His family had "memories, sweet memories of her," he said. Mr Khan and his wife Safia Sultana have four other children aged from one to 12.
Detective Chief Superintendent Brian Steele of West Yorkshire Police said: "A poor young girl clearly suffering from a terrible illness has died in circumstances that we cannot understand at the present time."Police have not ruled out that Naazish may have died of natural causes.