Anthony O’Donohue was the last passenger to board the bus driven by Manmeet Sharma at Moorooka in Brisbane’s south about 9am on October 28, 2016.

He was holding a backpack containing a plastic bottle filled with the flammable fuel which he lit and threw on Mr Sharma.

The 29-year-old driver, also known as Manmeet Alisher, was immediately engulfed in flames, while the bus filled with thick black smoke.

Fourteen passengers escaped the vehicle with help from passers-by.

O’Donohue was immediately identified as responsible as he sat at the bus stop with burns to his legs.

The treatment he received from mental health services is the focus of an inquest that began in the Coroners Court in Brisbane on Monday.

His case manager for four years, clinical nurse Jeremy Gourlay said O’Donohue – his first client with a relatively rare delusional disorder – had made threats about taking an officer’s gun and using it to shoot people at a police station in 2011.

Gourlay told the inquest he never felt threatened by his client, who expressed disgruntlement with unions saying they would “get what’s coming for them”.

O’Donohue didn’t have any plan or intent, but claimed unionists had infiltrated public services, limiting his career and life opportunities, the inquest was told.

Unknown to authorities it appears he stopped taking anti-psychotic medication in 2014, although he continued to fill out scripts,

Psychiatrist Dr Janice De-Souza Gomes revoked O’Donohue’s involuntary treatment order in December 2014, with the inquest being told he no longer met the criteria.

He continued to get care voluntarily until his discharge from the mental health service on August 1, 2016.

De-Souza Gomes said she would have preferred to have him followed up by a psychologist or psychiatrist, but he refused and his risk of harming himself or others was low.

“It’s always a possibility that patients will relapse,” she added, saying O’Donohue was given information about who he could approach if he needed help.

On August 31 O’Donohue tried to make a further appointment but was told he had been closed to the service.

Gourlay tried to phone O’Donohue back, but the call went unanswered.

O’Donohue was charged with murder but declared of unsound mind and not criminally responsible for his actions by Queensland’s Mental Health Court.

That court ordered he be held in a mental health facility for at least a decade, the first time such an order had been made.

Sharma’s brother Amit, who has come from India to attend the inquest, said outside court his brother was “always smiling and happy”.