The attack left Mokbel critically hurt with chest wounds and brain injuries, and he was in a coma for five days.
During a plea hearing in the County Court of Melbourne on Tuesday, forensic psychologist Carla Ferrari said she had prepared a report after assessing Teuira in November last year.
She diagnosed him with post-traumatic stress disorder based on childhood trauma.
Ms Ferrari said Teuira had tried to contact his family on the phone the day before the attack on Mokbel, because they had planned to visit him, but he could not reach them.
This “reinforced sentiments of rejection and abandonment from his family, which brought back a lot of memories from the past and underlying anger”, she said.
“He had underlying anger and negative emotion from the day before. Next day his ‘family in prison’ is taken to be threatened, which then evokes that response again.
“They are … being made to look weak and vulnerable, which then evokes responses of, ‘I need to stand up and do something.’ “
She said people with PTSD were more likely to have disproportionate responses to negative emotions.
However, Judge Liz Gaynor said she found it hard to accept the offender’s PTSD was linked to the attack.
“I’m finding it really difficult to accept there is a link between PTSD and the fact he felt abandoned and rejected … and what must have been a group response to the article the next day,” she said.
She said prison has a “very hierarchical, strict structure in which loyalties are demanding” and it was “run by all sorts of rules and regulations that are entirely reasonable to inhabitants and unreasonable to society at large”.
“So [the offenders] are brought into that strict culture, and that strict culture involves judgments and behaviours which in the outside world are simply unacceptable but are de rigueur in the jail,” she said. “So out comes the Herald Sun article. It’s a complete affront to the status of the Islander cohort in that jail.
“You have to assert yourself in no uncertain terms. That, in the jail, is not considered a disproportionate response. Indeed, it’s the way to go.”
Barrister Simon Moglia, for Teuira, conceded that while his client’s PTSD did not directly cause his offending, the disproportionate response to the “perceived indignity encapsulated in that article directed at his community” should be taken into account when sentencing.
“My submission is PTSD and the symptoms lowered his capacity to make a proportionate response. It doesn’t cause it in the strict sense, but neither is it irrelevant,” he said.
Prosecutor Kristie Churchill rejected this submission and said both men’s offending was in the “very upper end of serious injury”.
“There’s no insight, there’s no remorse, there’s no explanation as to why. We are all left here hypothesising,” she said.
“There is some planning to some degree before. This isn’t simply a spontaneous attack in the face of confrontation. It’s planned, they waited for him and attacked him directly.”
Lawyers for both men raised concerns about the effect coronavirus restrictions were having on their clients, due to the reduction of privileges in jail and the lack of family visits.
The pair have also pleaded guilty to recklessly causing injury relating to another prisoner who was stabbed in the side trying to help Mokbel.
Judge Gaynor will sentence the two men on May 29.
Simone is a crime reporter for The Age. Most recently she covered breaking news for The Age, and before that for The Australian in Melbourne.