Child killer Rick Thorburn is sentenced to life in jail for murdering his 12-year-old foster daughter, Tiahleigh Palmer, who he killed to protect his son after he had sex with her and feared she was pregnant.

The 57-year-old will not be eligible for parole until September, 2036.

Prosecutor Carl Heaton QC told the court Thorburn had told his family “it was all taken care of” after he murdered Tiahleigh, to “protect” Trent from criminal charges, later dumping her body on a riverbank.

Trent Thorburn was sentenced to four years in jail for incest, perjury and attempting to pervert the course of justice. He was released in late January 2018, after serving 16 months.

Tiahleigh was reported missing on October 30, 2015 after the Thorburns told police she had not returned from school.

Her body was found six days later on the banks of the Pimpama River on Queensland’s Gold Coast.

When her body was eventually found on November 5, the cause of death could not be determined because of the state of decomposition.

The Supreme Court heard Tiahleigh was mostly naked when her body was found and there was a bruise on her scalp.

‘Cold, calculating and callous’

In handing down the sentence, Justice David Boddice described Thorburn’s offending as “cold, calculating and callous”.

“Your offending involves truly appalling conduct,” Justice Boddice said.

“You showed no respect for her, even in death — you murdered this defenceless child who relied on you for protection.”

Rick Thorburn killed 12-year-old Tiahleigh Palmer in 2015. Photo: AAP

The court heard Thorburn “feigned concern” and murdered Tiahleigh “to protect your son”.

Thorburn looked straight ahead in court as Justice Boddice told him the crime was “made more shocking by the deliberateness of your actions” and the willingness to get his family to defend his “despicable behaviour”.

While still inside the courthouse, Tiahleigh’s family held a prayer session, clapping and hugging each other.

Thorburn formally pleaded guilty at Friday’s hearing to Tiahleigh’s murder, along with perjury, attempting to pervert the course of justice, and interference with a corpse.

He wiped tears from his eyes as he admitted to murdering Tiahleigh and disposing of her body.

Mr Heaton told the court the killing took place while his wife Julene, Trent and another son Joshua were out of the family home late on October 29, 2015.

“Richard explained they would do things like they normally do. He told the family ‘we have to protect Trent, we need to keep a story to ourselves that she went to school [the following day]’,” Mr Heaton said.

Rick told them: “I have her hidden and I’m going to get rid of her tomorrow night. I’m going to leave home tomorrow morning, as if I’m going off to school as if I’m going to collect some car parts.”

“Tomorrow night I don’t want you boys home so I can get rid of Tiah’s body. I know a good place.”

Mr Heaton told the court Thorburn had told his wife: “Go to bed. Tomorrow will be a normal day.”

All four family members, including foster mother Julene and sons Trent and Joshua, were arrested in September 2016, nearly a year after Tiahleigh was murdered.

Three of them were found guilty of perjury and attempting to pervert the course of justice, with Julene Thorburn identified as the person who orchestrated a plan to cover up the crime.

‘No sentence will ever be enough’

Tiahleigh’s biological mother Cindy Palmer and many supporters sat in the court gallery a few metres behind Thorburn.

Outside court, Ms Palmer said she needed time to process the sentence and grieve with her family in private.

“Today’s outcome marks a long and painful fight for justice for Tiahleigh,” Ms Palmer said.

Tiahleigh’s biological mother arrives at a Brisbane court. Photo: AAP

“But as her mother, no sentence will ever be enough.”

She described Tiahleigh as a beautiful young girl who had her whole life to look forward to.

“Rick Thorburn took that away from me, from our family and most importantly from Tiahleigh,” she said.

Detective Superintendent Kerry Johnson said outside court that he hoped Thorburn would spend time in his cell thinking about what he had done.

“A 12-year-old girl, and as we know had her whole future ahead of her, that was cut short by this person,” he said.

“It is the ultimate act of betrayal where she was put in a foster care situation and the people who were supposed to provide and care for her were the very same people who allowed this to happen.

“It’s an absolute tragedy and inexcusable.”

‘Stick to the story’: Thorburn orders family to keep quiet

Mr Heaton said the police investigation “failed to uncover any tangible evidence” until about seven months after Tiahleigh’s death when an anonymous Crime Stoppers tip came in.

An anonymous tip detailed a secret family meeting held by the Thorburns, and included information that Trent Thorburn had confessed to having sex with his foster sister while talking to his cousin on Facebook.

This new information sparked a Crime and Corruption Commission (CCC) investigation.

Police then called the Thorburns before a CCC hearing where the family maintained that Tiahleigh had been dropped at school and was not heard from since.

Listening devices were subsequently installed in the Thorburn’s house that detected Thorburn instructing his family to “stick to the story” and keep Tiahleigh’s relationship with Trent quiet.

“Richard Thorburn has never directly made any admissions to having murdered Tiah, but the contents of them indicate that is what has happened,” Mr Heaton told the court.

Mr Heaton told the court some of the conversations included:

Julene Thorburn to Joshua Thorburn: Dad made the decision to go down that path and unfortunately we are going to have to live with it.

Rick Thorburn to Julene: No, but don’t you tell anyone ever, no matter what – that’s when things will f–k up.

Julene responded: No I’m not, this cannot go on like this, it’s not fair to everyone.

Mr Heaton called for a no parole period to be given to Thorburn for the offence of murder.

Thorburn’s defence barrister said his client had been a child in care himself after his mother died when he was nine years old and had spent time in juvenile institutions and on the streets.

The defence gave a letter from Thorburn to Justice Boddice saying “not a day goes by that he’s not haunted by what he has done”.

“Your letter today expresses your profound remorse for that conduct,” Justice Boddice said.

Minister Shannon Fentiman who was the Child Safety Minister at the time of her disappearance pulled out of a scheduled press conference at a TAFE centre in Brisbane’s south side this morning, 15 minutes after it was meant to start.

Current Child Safety Minister Di Farmer has released a statement saying Tiahleigh Palmer was a victim of an “evil crime”.

“This was despite Queensland having a strong and robust system for the approval of foster carers,” she said.

-ABC