The key figures in the Tiahleigh murder

KEY FIGURES IN TIAHLEIGH PALMER CASE:

TIAHLEIGH PALMER

* Twelve-year-old Marsden High schoolgirl, last seen alive on October 30, 2015

* Murdered by foster father Rick Thorburn after his son Trent confessed to having sex with her

* Body dumped and left to decompose in the Pimpama River where she was found a week later

* Autopsy couldn't reveal cause of death; only discernible injury was bruise on her skull

* First went into foster care when she was seven because her mother was unable to care for her

CINDY PALMER

* Tiahleigh's biological mother, she said no sentence would make up for loss of her "happy" and "angelic" daughter

* "You lied and covered up the fact that you had sex with my 12-year-old daughter, and even went to the extent of coming to her funeral and dancing at the service," she wrote about Trent Thorburn in a victim impact statement

* "You hugged me and my family and cried at what happened to my daughter knowing full well what you had done."

* It has been reported she spent time in jail for minor offences

RICK THORBURN

* Charged in September 2016 with murdering Tialeigh disposing of her body

* Initially sought a judge-alone trial due to publicity but in March indicated he would plead guilty to all charges

* Murdered her to cover up fact his son had sex with the 12-year-old and feared she was pregnant

* Sentenced to life with minimum of 20 years

TRENT THORBURN

* Confessed to his mother in late October 2015 he'd had sex with Tiahleigh and feared she was pregnant

* Sentenced to a maximum four years jail after pleading guilty to four charges including incest

* Released on parole in January 2018 after 16 months in custody, with sentence wholly suspended for five years

JULENE THORBURN

* Electronic surveillance device planted in family home picked her up saying they would have to "stick to the same story" after questions were raised about Tiahleigh's disappearance

* Sentenced to at least six months in jail in November 2017 after pleading guilty to perjury and attempting to pervert the course of justice.

* Court found she lied to authorities investigating Tiahleigh's disappearance to protect her "family and lifestyle", because of the "shame and embarrassment" as well as desire to protect Trent

JOSHUA THORBURN

* The Thorburn's eldest son, sentenced to three months in jail in July after pleading guilty to same charges as his mother

* Came home on night of Tialeigh's murder to a family meeting where she was discussed.

* His lawyers claimed he lied to police twice because he was terrified of his father