Queensland's child safety minister says nothing can be done to protect children in foster care from abuse or death at the hands of a guardian like Rick Thorburn.
Thorburn will spend at least 20 years behind bars after admitting on Friday that he murdered his 12-year-old foster daughter and dumped her body in a Gold Coast river.
Tiahleigh Palmer's death in 2015 sparked a series of reviews into Queensland's foster care system, and the way carers are approved.
But Child Safety Minister Di Farmer says it is impossible for departmental staff to predict how carers will behave toward children under their watch.
"We can never ever factor in the depths of depravity of a human being like Rick Thorburn," Ms Farmer told reporters after the sentencing.
"There was nothing in Rick Thorburn's history, there was nothing in our assessment process that could have predicted what he was going to do to Tiahleigh."
Ms Farmer says foster care approval systems were strong and robust at the time of Tiahleigh's death, and she was the victim of an evil crime.
The government has come under fire from representatives of the state's foster kids for not acting soon enough to introduce more than 100 recommendations spawned from reviews sparked by the case.
Foster Care Queensland executive director Bryan Smith said it was vital that reforms flowing from those reviews take effect quicker.
"While the reforms are good and will be solid, we just want them in place," he's told AAP.
Jacqui Reed, chief executive of the CREATE Foundation, commended government efforts to improve the system, but said its own suggestions were being ignored.
It has proposed allowing child safety officers to make unannounced visits to foster families to get a more genuine understanding of the relationship between carers and children.
It also wants a less bureaucratic approach to the way caseworkers build relationships with children.
"Out-of-home care systems around Australia need to learn lessons from the horrific circumstances surrounding Tiahleigh Palmer's death," Ms Reed told AAP.
She said systemic changes were needed to ensure children have a safety network to call on "when things aren't right".
Bravehearts founder Hetty Johnston admitted issues before the government were complex, but there was no reason not to close gaps within the system.
"While those gaps are still there, human nature says someone will find them and hurt another child," she said.
Queensland, which has more than 8000 children in foster care, has already introduced tougher screening procedures for foster carers, but other changes are yet to be enforced.
Australian Associated Press
