One of the long-term friends, Kieahn Kotiau, had multiple chances to tell police and family members about the alleged murder, but continued to assist her brother in the disposal of her body in February 2019.

Kotiau, 20, faced the Supreme Court in Melbourne for a plea hearing on Monday.

She pleaded guilty to concealing the body of Ballarat woman Tamara Farrell in her vehicle, assisting in the disposal of her body and assisting in hiding evidentiary items.

Kotiau helped remove Ms Farrell's body and drove with her brother to a rural location near Sale, where Ms Farrell's body was allegedly doused with petrol and set alight.

This was after the Kotiau siblings, Ms Farrell and her housemate had spent the night drinking and playing games together at Ms Farrell's home, the court heard.

Ms Farrell was 32-years-old at the time of her death in February, 2019 and had moved to Ballarat after starting a job with Ballarat Coachlines in 2018.

Crown prosecutor Patrick Bourke said Ms Farrell and her three siblings had grown up with Kotiau and her family as their mothers were 'lifelong friends' and the children referred to each other as 'cousins'.

The court heard Ms Farrell was the eldest of the children and at times, babysat the accused and her brother.

In the summary of offending, Mr Bourke said Ms Farrell had invited Kotiau and her brother to her Canadian home for a games night on Saturday February 16, 2019.

They arrived at 11pm and played and drank alcohol for about six hours, before going to bed around 6am on Sunday.

Mr Bourke said Kotiau fell asleep and woke up around 12.30pm on Sunday.

Later that afternoon she saw Ms Farrell's naked body lying on the floor of her bathroom and noticed the right side of her face was dark like it was bruised.

The court heard Kotiau followed orders to ensure Ms Farrell's housemate did not see Ms Farrell's body while it was loaded into the boot of her car.

Mr Bourke said Kotiau drove to Altona with her brother and stopped at a petrol station where he allegedly filled the car and a petrol container.

Kotiau stayed in the car at the petrol station, with Ms Farrell's body in the boot, while her brother walked home to get money to pay for the petrol.

The court heard Protective Service Officers parked near Kotiau and entered the store, but she made no efforts to tell officers about Ms Farrell.

Mr Bourke said Kotiau then drove to their family home, where her brother allegedly collected a bag of clothes, a hammer and a chisel.

He said she then followed orders to drive to Ararat, but missed the exit and pretended to be lost, before continuing driving to Nambrok, a rural location near Sale, where the body was allegedly dumped.

The court heard Kotiau said they left the scene while Ms Farrell's body was still alight and stopped at Yarragon on the way back to get changed into clean clothes.

Mr Bourke said Kotiau and her brother then returned to the family home.

Kotiau went to work on Monday and made no attempts to tell anyone what had happened until police arrived at the family's home on Monday evening.

The court heard Kotiau was distressed and upset, made a statement to police and directed them to Ms Farrell's body.

Police found Ms Farrell's body dumped and burnt, mostly devoid of clothing, in a property by the side of the road in Nambrok under a windbreak of trees.

Items from Ms Farrell's home along with a bag containing Ms Farrell's lower jaw, teeth, hair and a pendant were found under a railway bridge in Altona.

Defence barrister Robert Thyssen said Kotiau had made full and frank admissions to police and had entered a plea of guilty at the earliest opportunity.

He said the accused was a young offender, now 20-years-old, and had no prior convictions.

The court heard Kotiau had also agreed to give evidence at her brother's trial if required.

"She was young, immature, in an extremely stressful and confusing situation, one where she felt ill-equipped to deal with," Mr Thyssen said.

"It doesn't excuse her role, but it does put her situation in some context."

Mr Thyssen said she was 'nervous, distressed and confused' during the offending and did make some attempts to alert others to the deceased, including beginning to drive to the police station and driving on a toll road with the intention of creating a record.

The court heard Kotiau worked as an administrator in a nursing home at the time of the offending and was studying a Bachelor of Business online.

Mr Thyssen said since the offending, her employment and study had been terminated and she had been seeking assistance from a psychologist who determined she was suffering post traumatic stress disorder.

He said Kotiau had good prospects of rehabilitation and submitted a community corrections order should be imposed as an appropriate sentence.

Justice James Elliott questioned the defence about the number of times throughout the ordeal the accused could have raised the alarm and escaped from her brother.

Mr Thyssen referred to Kotiau's statement to police when she said "he scares me a lot of the time, just 'cause he's very unpredictable".

In prosecution submissions, Mr Bourke said this was a 'serious example' of assisting an offender because Kotiau was 'assisting with the belief her brother killed the deceased' and the assistance was over a 'significant' period of time.

He said the accused was not directly involved in the acts of burning and other violent acts upon the body, but they happened during the time she was assisting.

"She has driven him to that site, driven to the petrol station, handed over the hammer," he said.

"...really, all she had to do was say something.... there are times where she's on her own, there are times when she's with the car on her own, and there are times where she's with a number of other people that she has access to, including Protection Service Officers at the petrol station."

Mr Bourke said Kotiau was entitled to the 'informer's discount' in agreeing to give evidence at her brother's trial, but he referred to the 'breach of trust' between the accused and the deceased's family.

"She knew the deceased very well, was very close to her and was very close to all of her family," he said.

"In my submission, that goes to the court's assessment of this accused's moral culpability when she decides to do what she decides to do."

Mr Bourke submitted some duration of imprisonment was within the appropriate range of sentencing.

The charge of 'assist offender' carries a maximum penalty of 20 years imprisonment.

Kotiau has been and remains on bail.

Justice Elliott adjourned the case with a date to be fixed for sentencing.

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