A Queensland mum didn't report the death of her young daughter and the body wasn't found until a concerned neighbour arrived to check on the pair, police say.
It's been almost two years since the neighbour found 11-year-old Sophie Smith dead in a bed at her family's home at Mount Cotton on August 1, 2019.
She had no injuries and no underlying health problems. Her mother was found inside the home with what police alleged at the time were self-inflicted injuries.
Queensland Police initially said Sophie's death was not suspicious.
But on Monday detectives revealed they have long treated the case as a possible crime, after unearthing "inconsistencies" in autopsy results and testimonies.
Detective Inspector Stephen Hollands says investigators want to hear from anyone who might know more about Sophie's death, her family and the events leading up to the discovery of her body.
Sophie's mother and father have been interviewed several times during the course of the investigation. The mother's most recent interview was in the last month.
Sophie's body was found after her father, Edward, repeatedly tried to check in on his family while he was out of town for work but couldn't get through.
He eventually contacted a neighbour and asked them to go to the home to make sure everything was okay, Mr Hollands told reporters.
"Her body was found in the master bedroom of the house. An autopsy the following day found Sophie did not appear to suffer any injury or medical condition that would explain her death," Mr Hollands said.
"Nicole is Sophie's mother. She was present in the house at the time Sophie was located, and taken to Redlands Hospital."
The last proof of life detectives have is a photo of Sophie, taken by her mother and shared with family members, on the night of Saturday, July 27 - five days before her body was found on August 1.
The mother told detectives she was at home for the majority of the five day period but had left the house for short period of time, he said.
He said the investigation was focused on "certain inconsistencies, in witness versions and autopsy results", including a toxicology report.
He said Sophie had attended school "sporadically" leading up to her death.
"The investigation has been progressing slowly and steadily but we are at that time ... where it's important that we appeal to the community and ask if there's anything they could assist us with."
AAP is seeking comment from family members.
