A man used a baseball bat to kill a father-of-seven in the mistaken belief his victim was responsible for the death of his own father in the Black Saturday bushfires, a court has heard.
James William Colin Gibson, 20, was in July found guilty of murder after clubbing Glen Sullivan to the back of the head in the home of a mutual friend, Adam Charleston, in Tyers, near Traralgon, on the night of April 3 last year.
![James Gibson mistakenly believed Glen Sullivan was responsible for the death of his father in the Black Saturday bushfire.](/web/20160923133704im_/http://www.theage.com.au/content/dam/images/g/r/n/7/8/y/image.related.articleLeadwide.620x349.grn4vk.png/1474611228334.jpg)
Mr Sullivan, 41, later died in hospital.
The Supreme Court jury was told Gibson was in the grips of drug-induced psychosis when he attacked Mr Sullivan, having used ice earlier that night.
His lawyers argued he was experiencing a schizophrenic episode. Prosecutors now concede the young man has schizophrenia.
On Friday, prosecutor Campbell Thomson said the attack was unprovoked, from behind and on an unsuspecting person, whom Gibson mistakenly believed was to blame for the death of his own father in the Traralgon South bushfire on February 7, 2009.
Gibson yelled that Mr Sullivan "killed my dad" during the attack, the court heard.
"This is a young man who was psychotic as a result of drug taking when he mistakenly and deludedly thought this person had a connection in his father's death," Mr Thomson said.
"This is Mr Gibson believing he is acting out an act of revenge."
Gibson struck Mr Sullivan with the bat at least twice and at least once when he was on the floor, in front of two others.
Mr Thomson said the killer's culpability was high given he voluntarily took ice despite his mental-health problems, and had a history of using the drug around the times of previous violent offending.
But defence counsel John Kelly said his client was "quite divorced from reality at the time", which reduced responsibility.
Justice Michael Croucher agreed, and said he couldn't see how the young man's culpability wasn't reduced.
"It's hard to see how a person who is psychotic, whatever the cause, doesn't have a reduced moral culpability," he said.
Mr Kelly said Gibson idolised his father and never received adequate counselling at age 12 when his father died trying to protect his parents' property.
After his father's death Gibson began self-medicating with cannabis, the court heard, dropped out of school and later began using ice.
Ice made him feel "better", the court heard, but he also thought more about his father when under the effects of the drug.
Mr Sullivan's brother, Brett, wished Gibson would accept some responsibility but held little hope.
"I will never forgive him for what he has done," he said in a victim impact statement read to court.
Mr Sullivan recalled the shock of seeing his "bruised and battered" brother in hospital on life support, his own sorrow and the added torment at having to counsel his brother's children over their loss.
Glen Sullivan's father, Terry Sullivan, said he had hoped the trial would bring him some closure as he grieved for his son, but instead felt angry and betrayed at what he had to listen to in court.
"I have four children and I never thought I would see the day that I would bury any of them before me," he said.
Gibson, a former bricklayer, has spent 540 days in custody. He will be sentenced next month.