Mark Ludbrook, 54, stabbed Autumn Baker to death at his home in Melbourne's southwest as she tried to stop him from self-harming on August 3, 2023.
Ludbrook claimed his mind was altered by PCE, an illicit drug he had taken earlier that morning to manage pain from his rare neurological condition.
But Victorian Supreme Court jury found he was conscious of his actions and therefore guilty of murder.
His barrister Emily Clark on Friday said there was no dispute the PCE caused Ludbrook to act violently on the day of the murder.
But she argued Ludbrook could not have known the drug would affect him that way, given he had previously taken ketamine for pain management without issue.
"It seems he had been using (ketamine) daily and safely for a period of time," Ms Clark said.
"There is no foreseeable way for Mr Ludbrook to have known he would react that way."
The barrister argued Ludbrook's moral culpability was reduced as a result, noting the 54-year-old was also of previous good character.
Ludbrook's diagnosed transverse myelitis was also making his time in custody more difficult, Ms Clark said.
Ludbrook, who uses a wheelchair, required extensive physiotherapy to manage his pain and improve his mobility but that was limited in prison, the barrister said.
He was also only allowed to leave his cell for a few hours at a time and he did not have access to the prison computer, library, chapel or gym, Ms Clark said.
She argued Ludbrook had spent close to a year on bail before his murder trial without taking illicit substances or committing other offences, so his prospects of rehabilitation should be considered excellent.
His risk of reoffending was also low and the idea he would engage in similar behaviour again was "fanciful", Ms Clark said.
She pushed for Ludbrook to be sentenced to a longer-than-usual parole period, meaning he could be back out in the community sooner.
"When you look at the very high burden of imprisonment and the circumstances of the offending, this is a case where a very lengthy period on parole would not only serve Mr Ludbrook but the community as well," she said.
Justice James Gorton said the case was not straight forward and he would need some time to reflect on the matters.
Ludbrook will be sentenced at a later date.
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