LONDON — A mass killing by a British teenager who fatally stabbed three little girls and seriously injured 10 other people at a Taylor Swift-themed dance class in 2024 “could and should have been prevented” if his parents and state agencies had acted as his well-known fixation on violence escalated, according to a report released Monday.

Adrian Fulford, a retired judge who led a nine-week inquiry, issued a 763-page report that cataloged the many times parents or authorities could have intervened in Axel Rudakubana’s life to ultimately prevent him from carrying out killings that he said were unprecedented in the U.K. for their “extreme and very particular depravity.”

“One of the most striking conclusions from this inquiry’s extensive investigation is the sheer number of missed opportunities over many years to intervene meaningfully, which directly contributed to the failure to avert this disaster,” Fulford said. “The consequences were catastrophic.”

Rudakubana, who was 17 when he carried the attack in northwestern England, is serving a life sentence with no chance of parole for 52 years for killing Alice da Silva Aguiar, 9, Elsie Dot Stancombe, 7, and Bebe King, 6, and wounding eight children and two adults.

The attack in the town of Southport triggered days of disorder after far-right activists seized on incorrect reports that the attacker was a Muslim migrant who had recently arrived in the U.K. Rudakubana was born in Wales to Rwandan Christian parents.

The report made 67 recommendations to prevent future atrocities and British Prime Minister Keir Starmer has promised changes to correct the “systematic failures that led to this terrible event.”

“The report today is truly harrowing and profoundly disturbing,” Starmer said. “While nothing will ever bring these three little girls back, I’m determined to make the fundamental changes needed to keep the public safe.”

Police, social workers and educators were well aware of problems with Rudakubana.

He was convicted in 2019, aged 13, of assaulting another child at school with a hockey stick and placed under supervision of a local service for youth offenders. He was referred to the government’s anti-extremism program, Prevent, three times between 2019 and 2021 for expressing interest in school shootings, the 2017 London Bridge terror attack, the Irish Republican Army and the Middle East. Each time, the case was closed because he was not considered susceptible to becoming a terrorist.

During that same period, local police were called to his home five times over unspecified concerns about his behavior. He was given mental health and educational support, but later appeared to have stopped engaging with social workers. He was expelled after taking a knife to school and hardly ever attended a subsequent school.

“Far too often, AR’s ‘case’ was passed from one public sector agency to another in an inappropriate merry-go-round of referrals, assessments, case-closures and ‘hand-offs,’” said Fulford who only used the killer’s initials.

Fulford highlighted an incident in March 2022 when Rudakubana was caught on a bus with a knife and told police he wanted to stab someone and admitted trying to make poison.

Taken together, they should have sparked an arrest that would likely have led to a search of his house that would have discovered he had bought seeds to make the biological toxin ricin and downloaded terrorist material on his computer, Fulford said.

Rudakubana was not arrested and was released to his parents, who feared him and repeatedly failed to report the various knives he had purchased, his troubling behavior and threats he had made.

While Fulford outlined several failings by Rudakubana’s parents that could have prevented the tragedy, he said they should not be vilified for what had become a challenging situation.

“Their life at home must have become little short of a nightmare given, to use the words of his own father, AR had turned into a ‘monster,’” Fulford said.

Following the Southport attack, police searched Rudakubana’s home and discovered the ricin hidden under his bed and a downloaded document which was described as an al-Qaida training manual.

Police concluded his crimes should not be classed as terrorism because he had no discernible political or religious cause or motivation.

Starmer had previously said case showed that “terrorism has changed” and the law might need to be changed to deal with the threat of “extreme violence carried out by loners, misfits, young men in their bedrooms.”