Shaye Kotiau appears in Ballarat court over Tamara Farrell's murder

The two siblings alleged to have been involved in the death of Ms Farrell, from Canadian, faced a committal hearing in Ballarat on Tuesday morning.

Shaye Kotiau, 22, and Kieahn Kotiau, 19, both appeared in court, where lawyers presented evidence about his mental condition.

Police allege the 31-year-old Farrell was murdered in her Canadian home on February 17 by Mr Kotiau and dumped 300 kilometres away from Ballarat at Nambrok, near Sale.

Her remains were located days later at that location.

Police allege further remains of Ms Farrell's body were found in a bag under a bridge in Altona North in May.

Kieahn Kotiau indicated she would plead guilty to concealing Ms Farrell's body in her vehicle, assisting in the disposal of her body, as well as assisting in hiding evidentiary items.

Dr Jason Schreiber, from the Victorian Institute of Forensic Medicine, told the court he had evaluated Mr Kotiau after his arrest because police were concerned about his mental fitness for interview.

The forensic physician gave evidence that the 22-year-old had no physical injuries, but said the man had an 'odd stare' and his eyes were rolling around in his head.

Mr Kotiau told the doctor during the assessment he believed he had psychic foresight, had intentions of killing a list of people, and said he knew he would "go to prison now for what he did".

"When he came under police custody, he was staring, quiet, acting strange," Dr Schreiber said. "There were psychotic elements in his presentation.

"It took a long time for him to react, there was hesitation ... it was not the way a flow would usually be seen in the conversation."

After the interview, Dr Schreiber recommended the man be assessed by a mental health professional, as Mr Kotiau has discussed suicidal ideation.

The court heard on Tuesday that Mr Kotiau reserved his right to plead in his current mental state, with his defence lawyer Jarrod Williams saying he had "some concerns around fitness", but they were content to proceed with the hearing.

Altona-based psychologist Peter Abraham met with the 22-year-old on February 4 and 11, in the weeks before the alleged murder, and said the accused was "very reluctant" to speak and he couldn't get much information out of him.

Mr Kotiau's mother had booked the appointment, describing her son to the psychologist as "shy", with a GP's referral stating he had anger issues and an unspecified mental disorder.

Mr Abraham said the man had his head down for much of their first meeting, and would look up with his eyes while speaking, indicating caution. Mr Kotiau told the psychologist he was bullied in school, but did not present as "delusional".

"What he did say was very quietly spoken and very brief. Usually when someone would come to see someone like myself, they will open up and want to talk, but I got the opposite (from Mr Kotiau)," Mr Abraham said.

"The thought form being presented to me was quite coherent."

The accused man was assessed to have mild depression and anxiety issues.

Appearing in a black and white floral dress and a black blazer, Ms Kotiau did not speak at the committal hearing except when entering her plea of guilty.

The woman was bailed with conditions around reporting to the Altona North Police Station and surrendering any passports held. She will appear in the Supreme Court in Melbourne on Nov 6 for a directions hearing.