Kayla Dawson instigated the murder of Jason Galleghan, 16, in western Sydney in August 2021 after wrongly suspecting he had stolen her Apple AirPods.
Two months before being handed a 20-year sentence over the teen's killing in July 2024, Dawson, now aged 23, was seen trying to die by suicide in her Silverwater prison cell.
Four prison officers attended to stop her.
They removed objects from Dawson's cell, given the self-harm attempt, before trying to remove her clothing and get her into a safety smock.
During the tussle, she was seen growling before biting a senior correctional superintendent on the arm, drawing blood.
Dawson was issued a nine-month sentence for the assault at Burwood Local Court on Wednesday, where details of the incident were revealed.
Because the Director of Public Prosecutions has chosen not to move the matter to the District Court, legislation meant the sentence will be served alongside Dawson's longer sentence for murder rather than extending it, Judge Chris Halburd noted.
"This court can't impose a meaningful decision or meaningful penalty on this defendant for a serious assault on a prison officer," he said.
"And it's just really unfortunate."
Dawson wore prison greens, with her brown hair tied in a bun, as she watched Wednesday's sentence from prison by audio-visual link.
The judge said the murderer had previously been sentenced for a separate prison assault, and an escape attempt, before being sentenced for murder.
He warned Dawson that any further offending would carry consequences.
"Instead of just getting a jail sentence that doesn't affect your release date, it'll start to add onto the end. Do you understand that?" he asked her.
"Yes," Dawson replied before the video link was turned off.
Her lawyer Daniel Brown earlier argued Dawson was in a highly-agitated state at the time of the assault, which was spontaneous.
Dawson had been diagnosed with a mild intellectual disability, attention deficit hyperactivity disorder, Tourette syndrome and impaired decision-making skills, he said.
Jason was aged 16 when he was severely bashed by Richard Sione, 32, and a group of youths at Dawson's Doonside home.
He was left alone on the floor wearing nothing but his underwear and died from his injuries two days later.
At a sentence hearing in July 2024, Jason's mother Rachel Galleghan spoke of the pain, trauma and heartbreak that her son's death had caused.
She urged the court to impose life sentences on both Dawson and Sione.
Because of her intellectual disabilities, Dawson was given a shorter non-parole period of 13 years for her 20-year head sentence.
She will be eligible for release on August 7, 2034.
As the adult in the room who started the physical bashing, Sione was sentenced to 32 years with a non-parole period of 24 years.
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