The brother of the Southport killer has spoken for the first time about the 'most immense pain, anguish and grief' caused by his sibling's attack.Dion Rudakubana, 21, told the public inquiry investigating his younger brother Axel's crimes that he wanted to help it investigate if officials could have done more to prevent the atrocity.In his first public comments since the attack last July, he said Rudakubana had become 'progressively more isolated' after being expelled from school, aged 13, in October 2019.Despite being under the care of mental health professionals for three years, he had only been diagnosed with autism and anxiety, and was officially discharged from their care six days before the atrocity.Rudakubana was also effectively a recluse, having not been to school for more than two years. Instead he spent most of his days in his bedroom watching violent videos.Bebe King, six, Elsie Dot Stancombe, seven, and Alice da Silva Aguiar, nine, were all murdered by 17-year-old Rudakubana, who is not being referred to by name in the hearings and instead is being known by his 'AR' initials, when he ran amok at the Taylor Swift-themed holiday club.He admitted murder and was jailed for a minimum of 52 years at Liverpool Crown Court, in January.In a written statement to the inquiry, Jacqueline Carey KC, representing Dion, said he wanted the various agencies involved with his brother, including social services and the child and adolescent mental health services (CAHMS), to explore whether they could have 'intervened' in the lead up to stop it happening. Bebe King, six, Elsie Dot Stancombe, seven, and Alice da Silva Aguiar, nine, were all murdered in the atrocity on July 29, 2024 Chairman Sir Adrian Fulford is overseeing the inquiry at Liverpool Town HallThe barrister said: 'To this end, Dion wholeheartedly supports the inquiry's aim to identify lessons which will minimise the prospect of such harm being caused in the future.'The inquiry is examining how Rudakubana, who had a known obsession with knives and extreme violence, was able to carry out what inquiry chairman Sir Adrian Fulford has described as 'one of the most egregious crimes in our country's history'.Ms Carey said Dion, who uses a wheelchair, 'was wholly unlike his brother – a thoughtful young man, of good character, studying at university.'In the statement, she said he had had 'limited interaction' with Rudakubana in the years before because he was studying for a degree in mathematics at Warwick University and living away from the family home, in Banks, near Southport.However, he had come back the weekend before the atrocity and had provided a full statement to police about 'what AR (Rudakubana) was like that weekend and indeed what AR was like in the years preceding the incident.'Ms Carey said Dion wanted to help the inquiry because his brother's actions had 'caused the most immense pain, anguish and grief to the lives of so many people'. The lawyer also said that, although he would not be attending the hearings in person because of his disability, he would be following them remotely.'His absence from the hearing room should not however be taken as indicating an indifference to the evidence being called or be taken as any discourtesy to the chair, core participants and the witnesses,' she added.The inquiry has heard that Rudakubana's problems began when he was expelled from The Range High School, in Formby, in October 2019, after he admitted bringing a knife into school premises 'on at least ten occasions'.He claimed he was being bullied and was later convicted of returning to the school two months later and attacking a fellow pupil with a hockey stick.Rudakubana was moved to a special school, where he continued to cause concern and was referred to Prevent, the Government's counter-extremism programme three times because of his consumption of violence on the internet.But when the Covid-19 pandemic hit, in March 2020, his attendance deteriorated and, although he returned sporadically to lessons and was eventually placed on the roll of another special school, he hadn't been to classes for 30 months before the attack.Specialists also raised concerns about Rudakubana's Rwandan-born parents, who the inquiry has heard apparently signed for knives and machetes that their son illegally ordered online.Psychiatrists complained about the behaviour of his 'intimidating' father, Alphonse, 49, and social workers witnessed 'tension' during home visits.The inquiry has been told mental health professionals carried out a risk assessment of Rudakubana on July 23 last year, six days before the killings, when he was discharged. The findings of that assessment - the third in four years - have not been disclosed.The inquiry, at Liverpool Town Hall, continues.