THE mother of Tiahleigh Palmer is calling for change after spotting the sons of her daughter's murderer in the audience of a youth cheerleading competition.

Earlier this week Cindy Palmer, the biological mother of the murdered schoolgirl, revealed Trent and Joshua Thorburn had been spotted at Queensland's Winterfest Cheer and Dance Championships.

The two boys were jailed for helping to keep their foster sister's murder a secret and for lying to police about it before a microphone hidden in the Thorburn home revealed they all knew about the 12-year-old's brutal death.

If Tiahleigh hadn't been murdered by Trent and Joshua's dad Rick in 2015, it was likely she would've been there dancing at the Brisbane competition with the dozens of other young girls attending the event.

Speaking to 9 News, Ms Palmer described the brothers' reintegration into the dance community as "a big insult".

"Every day is a constant battle," she said.

"They have some nerve turning up there and blending in with the community as if nothing has happened."

Speaking specifically about Trent, who admitted to having sex with the underage Tialeigh, Ms Palmer said: "Now he's just watching other young children - it just doesn't sit right with me."

Last month, Rick Thorburn was sentenced to life in prison for murdering Tiahleigh in 2015 in what police claim was an attempt to cover up Trent having sex with Tiahleigh when she was 12.

On October 29, 2015, Trent had confided in a cousin via Facebook that he had had sex with Tiahleigh and was worried she might be pregnant.

Hours later, she was murdered by Rick and dumped on the banks of the Pimpama River.

The entire family, included Rick's wife Julene, was arrested in September 2016.

Trent, who admitted to having sex with his foster sister, was jailed in September 2017 for a maximum of four years after pleading guilty at the Beenleigh District Court to incest, perjury and attempting to pervert the course of justice.

With time served, he was released on parole on January 19, 2018, after spending 16 months in prison.

The Thorburns' eldest son, Joshua, was sentenced to three months in jail in July 2017 after pleading guilty to the same charges as his mother.

Ms Palmer said a concerned parent called police after spotting the brothers in Brisbane Entertainment Centre but were told by officers they were not committing a crime by being there, despite Trent still being on parole.

Rick (left) is the only of the Thorburns still in prison after Tiahleigh’s death.
Rick (left) is the only of the Thorburns still in prison after Tiahleigh’s death.

The heartbroken mum wants to see children be better protected from convicted sex offenders.

"He's an animal and I honestly believe he's a predator," she said of Trent.

"It's pretty alarming that the police know he's a regular to these dance events and there's still nothing being done to protect all the other children that attend. He needs to be banned."

In the US, law requires police to release information about registered sex offenders to the public.

Known as Megan's Law, the federal law was created in response to the murder of Megan Kanka in 1994.

Megan was killed by a man living across the street from her, a man who had previously been convicted of sex crimes against small children.

After the seven-year-old's brutal death, her parents Richard and Maureen demanded a law that required there be mandatory community notification of sex offenders.