The mother of two little girls who died in a hot car parked outside their home is the first person to be charged under Queensland's new definition of murder.
Sisters Darcey-Helen, two, and Chloe-Ann, one, died inside a black station wagon parked across the front yard of their family home in Logan, south of Brisbane, on Saturday.
Kerri-Ann Conley, 27, has been remanded in custody on two counts of murder and has also been charged with possession of dangerous drugs and possession of drug utensils.
She is the first person to be charged under the state's expanded definition of murder, which includes reckless indifference to human life.
Premier Annastacia Palaszczuk said the family was known to the state's child safety department which had contact with them in the past.
Attorney-General Yvette D'ath will ask Cheryl Vardon, the Queensland Family and Child Commission's principal commissioner, to investigate.
Ms Palaszczuk said she would release those findings.
"The death of these two young girls is an absolute tragedy," she said on Monday.
"I was heartbroken when I heard about it. I think everybody would be in exactly the same position."
Conley did not appear when her matter was mentioned Brisbane Magistrates Court on Monday.
She was remanded to appear in Beenleigh Magistrates Court on December 11.
A man was assisting police with their inquiries but was no longer being questioned.
Paramedics were called to the home in the Waterford West suburb of Logan on Saturday afternoon but could not revive the sisters.
The girls were declared dead at the scene and police say they showed signs of being exposed to extreme heat.
Officers remained at the home on Sunday, piecing together what happened, as neighbours and community members left soft teddies and flowers at the front gate.
The station wagon remained parked across the yard.
Child Safety Minister Di Farmer has said her department would offer police any assistance needed in their investigation.
Deb Frecklington, leader of the Liberal National Party opposition, wants to know how the department was involved with the family and said the government would have her full support in overhauling the child safety system.