Stepmother of four-year-old Willow Dunn charged with murder

Police have arrested and charged a woman over the alleged murder of her four-year-old stepdaughter, Willow Dunn, whose body was found at a home in Brisbane.

Toddler Willow Dunn who was found dead in her cot at her Brisbane home. Source: Twitter

Police have arrested the stepmother of Brisbane girl Willow Dunn and charged her with murder.

The four-year-old's severely malnourished body was found at a Cannon Hill house last week.

Her father, Mark James Dunn, 43, has been charged with her murder and on Wednesday, police confirmed they had also arrested and charged Willow's stepmother with her murder.

The 43-year-old will appear in the Brisbane Magistrates Court later on Wednesday.

Detectives will continue to investigate the health, care and treatment of Willow, who had Down syndrome, in the days, weeks, months and years before she died.

"We have initiated investigations and inquiries in New South Wales, and in particular, we have advanced investigations that will continue and progress in South Australia," Detective Inspector Chris Knight said.

South Australia's major crime squad is involved.

The little girl's family moved from South Australia to Brisbane in 2017.

A pram is seen at a property in Cannon Hill, where the body of four-year-old Willow Dunn was found. Source: AAP

Police were faced with an "extremely confronting" scene at the home where Willow's body was found, with a post mortem finding she had suffered sustained mistreatment and had a litany of injuries.

Her death is being investigated by Cheryl Vardon, who leads the Queensland Family and Child Commission, to determine whether Queensland's child safety system failed.