- Shannon White will face the Brisbane Magistrates Court on a charge of murder
- Queensland police said detectives in South Australia and New South Wales were assisting the investigation
- Police say an autopsy revealed Willow was badly malnourished and suffered sustained mistreatment
Queensland police have charged four-year-old Willow Dunn's stepmother Shannon Leigh White with murder, more than a week after the child's body was found by emergency services at a house at Cannon Hill in Brisbane's south-east.
The girl's father, Mark James Dunn, was also charged with murder last week, with police alleging the child died around two days before the discovery of her body.
A post-mortem examination concluded Willow was experiencing "serious malnourishment" and other health issues "that indicated sustained mistreatment".
Ms White, 43, had her murder charge briefly mentioned in the Brisbane Magistrates Court on June 3.
Ms White did not appear in court and could not make an application for bail due to the nature of the charge.
Acting Detective Inspector Chris Knight said more than 25 detectives had been working on the investigation since Willow's body was discovered by emergency services on May 25.
He said Queensland police were working with detectives interstate to identify other people who knew the family.
"We have initiated investigations and inquiries in New South Wales and, in particular, we have advanced investigations that will continue and progress into South Australia," he said.
Inspector Knight said the South Australia Police major crime squad officers were assisting with the investigation.
"We know that members of Willow's family relocated from Adelaide to Brisbane in 2017 and we believe that there's value in identifying potential witnesses in South Australia.
"We [will] continue to obtain information from witnesses who are assisting police to build a clearer picture of the dynamics relating to Willow Dunn's family," Detective Inspector Knight said.
"Our investigative team are not yet satisfied that we've exhausted all inquiries.
"We will continue to investigate and evaluate all information that we come by so that we can make better informed decisions into the future."
Queensland police also confirmed officers were working with the Department of Child Safety and other government agencies in relation to this case.
"[The] Department of Child Safety have clearly been involved," Detective Inspector Knight said.
"We have had some interaction with them."