Tiahleigh Palmer's foster mother has pleaded guilty to perjury and attempting to pervert the course of justice, and been sentenced to 18 months in jail.
Julene Thorburn was found to have lied about Tiahleigh's death.
The Crown prosecutor alleged that she had lied to investigators as she was "protecting her family and lifestyle" and because of the "shame and embarrassment".
Tiahleigh disappeared on October 30, 2015 and her body was found six days later on the side of a river.
One of Ms Thorburn's sons, Trent Thorburn, was sentenced to four years jail for incest and perjury in September.
It is understood that Trent told his mother that he had had sex with 12-year-old Tiahleigh and feared that she may be pregnant.