The older brother of the perpetrator said his mother and father "were unable to handle" of their son and he was concerned his brother would fatally harm a person of their household, a official investigation has been told.
The attacker, aged 17 at the time, fatally attacked three children at a celebrity-themed dance class on July 29, 2024.
The Southport Inquiry, held at a civic building, learned the family member the older brother informed a acquaintance there was a possibility of his relative "taking action potentially fatal."
The investigation was told the brother wrote to his friend over the Discord messaging app: "The fights are scary because of the threat of someone dying."
He testified his sibling reminded him of the violent character in the film the Coen brothers film.
Rising Hostility
The hearing heard Dion was identified with a neuromuscular disorder at the twelve years old which resulted in him using a wheelchair and his mother and father providing increased care.
When asked by Richard Boyle, legal representative, if that altered their dynamic he replied: "Conflict arose that emerged."
The brother concurred his relative seemed to dislike this development.
He told the investigation that after the family moved from their previous home to their new location his relative's behavior worsened and he would have "violent outbursts."
The inquiry was informed Dion became "progressively concerned" of his sibling, who would strike him often.
He stated: "I was forced to be wary if I tried to communicate to him because each conflict could escalate into an confrontation."
'Serious fears'
The brother testified his relative became much more aggressive after he was dismissed from the educational institution in Formby, Merseyside, in autumn 2019.
The sibling left for university in the following period and the brothers spoke less and less "because he was not familiar with having me around."
Proceedings was told about a message the brother wrote to a acquaintance on the service in which he said his sibling was angered by him speaking late at night because of the limited soundproofing in their house.
He additionally informed his associate there was a risk of "his committing an act deadly."
He wrote: "Arguments are scary because of the danger of loss of life."
The counsel inquired: "You were genuinely concerned that your brother would fatally harm a member of your relatives?"
Dion responded: "If things escalated to that level."
The counsel questioned how his family responded to the perpetrator's aggression.
"There was no point to seek to penalize him," he stated. "Also, there was a heavy risk in proceeding that way.
"We discussed there was a widespread threat to safety in general conversation, if you try to confront him... it could provoke violence."
When Mr Boyle asked if his parents had been unable to handle of his relative, the brother concurred.
When asked about his brother being similar to a character from the picture the thriller, he stated: "I heard that character's meant to be a sociopath and that's why I employed that term there."
The brother testified the last interaction he had with his sibling was in the 2023 summer.
He confirmed that their mother and father requested the killer to take leave to him as he was departing to visit his associates and his sibling threw a bottle at him but the entryway shut before it made contact.
The inquiry ongoing.
