A second jury must consider the mental fitness of Melbourne's Bourke Street murder-accused driver after a first was unable to reach a verdict.
A Melbourne jury has been discharged after it was unable to agree whether Bourke Street murder-accused driver James "Dimitrious" Gargasoulas is mentally fit to stand trial.
Gargasoulas, 28, has faced an investigation hearing in the Supreme Court to determine if he is fit to face trial accused of running down pedestrians in Melbourne's CBD in January 2017, killing six people.
The jury of 12 deliberated for nearly four days after hearing expert evidence but they could not reach a unanimous decision and on Friday morning Justice Lex Lasry discharged them without a verdict.
"It is unfortunate we have got to this stage as it means the matter has to run again," Justice Lasry told the jurors.
"There are those among you who had strongly held views and you were right not to compromise.
"These things happen."
Justice Lasry said the fitness investigation would have to be repeated but suggested it could be unsuccessful a second time.
"Having heard all the evidence, firstly I am not surprised the jury struggled to reach a decision," he said.
Medical experts who testified in the case were divided over the question of Gargasoulas's fitness.
Two psychiatrists believe he is unfit for trial but one psychologist disagrees.
The defence argued Gargasoulas was "profoundly psychotic", believing he is the "messiah" sent to save the world from a comet, and should not stand trial.
But prosecutors said he should stand trial, arguing he understands his case and the trial process.
Friday is Justice Lasry's last day as a Supreme Court judge, as he must retire because of his age.
The Gargasoulas case will be handed to Justice Mark Weinberg.