MELBOURNE: A 48-year-old man accused of murdering Indian-origin bus driver and Punjabi singer Manmeet Alisher in Brisbane by dousing him in a flammable liquid has been confirmed as a former mental health patient and authorities have ordered a time-bound probe into the treatment given to him.

According to state Health Minister Cameron Dick, Anthony Mark Edward O'Donohue had undergone treatment at Queensland Health's mental health services.

The minister also announced launching an independent external inquiry into the treatment given to O'Donohue.

Dick said an independent investigation regarding his treatment will be conducted by forensic psychiatrist Paul Mullen and it would be completed within eight weeks.

Alisher's parents still don't know about his death. The family would wait until they returned his body to tell his sick mother and elderly father.

“We haven’t told the parents that he’s no more, we just say it’s an accident, he’s in a coma,” The Courier Mail reported their family spokesman Winnerjit Goldy as saying.

“The whole family is dependent on him,” Goldy said.

Meanwhile, Brisbane Lord Mayor Graham Quirk today said the attack was not racially motivated and extended support to the family and friends of 29-year-old Alisher, who was also popular as a Punjabi singer.

Quirk, who met the family and friends of Alishar, said there was no evidence that the attack was racially motivated and that residents of all races and backgrounds came together to show their support for the victim and Brisbane bus drivers.

However, Alisher's brother Amit Alisher, who had arrived from India yesterday, was quoted by ABC news as saying, "We suspect that it may be (racially motivated).

"We would like to see due process, we have faith in the Australian system," he said.

Quirk extended his support and deepest condolences to Alisher's family, on behalf of the Brisbane community.

The city council also announced establishing a fund to support Alisher's family and Alisher will also be honoured with a permanent memorial after consultation with the local community.

Health Minister Dick said, "To the extent possible, any findings and recommendations of this investigation will be released publicly.

"Queensland Health will also assist with any investigation or inquiry conducted by the Queensland Police Service and State Coroner in relation to this incident."

"Metro South Hospital and Health Service will conduct an internal review of treatment and services provided to the accused. This is a mandatory process in cases such as this," he said.

"However, given the very serious nature of this incident, I believe it is appropriate that there be an independent external investigation into the treatment provided within the health system to the accused," he added.

The Health Minister said, "Accordingly, I have requested the Director-General of Queensland Health to commission an independent investigation under the Hospital and Health Board Act 2011 regarding treatment provided to the accused."

Prime Minister Narendra Modi yesterday had raised with his Australian counterpart Malcolm Turnbull India's concern over the brutal killing of 29-year-old Alisher.

Turnbull had expressed shock at the killing and conveyed to Modi that the matter was being investigated.