The teenager who killed three young girls and injured 10 others in a knife attack at a dance class in Southport, England last summer, will be sentenced on Thursday.

Judge Julian Goose, presiding over the case, told the attacker, Axel Rudakubana, 18, that a life sentence would be inevitable after he pleaded guilty on Monday.

Since that court hearing, a portrait of a deeply troubled young man obsessed with violence emergedas well as the fact that he was on the radar of local authorities years ago knife attack in Southport on July 29a town north of Liverpool.

After the attack, Britain was rocked by a series of riots as misinformation about the attacker’s identity circulated on social media and messaging apps. False claims that he is an undocumented immigrant or newly arrived asylum seeker have increased far-right agitators. Mr Rudakubana is a British citizen born in Wales to Rwandan parents.

At the age of 13 and 14, he was referred three times to Prevent, the British counter-terrorism program, due to his fixation on violence, but these referrals were ultimately rejected because each time it was determined that he did not meet the threshold for intervention.

Prime Minister Keir Starmer said from Downing Street on Tuesday that the attack was a sign that terrorism was developing in the country and that young people were being radicalized by the “tidal wave of violence freely available on the Internet.”

“We also see acts of extreme violence committed by loners, misfits, young men in their bedrooms, accessing all sorts of material on the internet, desperate for notoriety,” said Mr. Starmer, noting that some have become “fixated on that extreme violence, seemingly for its own sake.”

Mr Rudakubana was also convicted of weapons charges for possessing the knife used in the attack, for producing a biological poison and for “possessing information” described as “of a kind which could be useful to a person committing or preparing an act of terrorism” after investigators found ricin, a deadly toxin, and a PDF file titled “Military Studies in Jihad Against Tyrants: Al Qaeda Training Manual” in his home.

The judge will not be able to sentence him to life in prison – a life sentence with the condition that the offender may never be released from prison on parole – because he was only 17 at the time of the fatal attack.

In 2019, Mr. Rudakubana was expelled after bringing a knife to school, and returned a few months later to attack a student with a hockey stick. He was then enrolled in a school for children with special needs.

The local protection agency said he struggled to integrate into his new school, and when the coronavirus pandemic began in 2020 and schools closed across Britain, his isolation deepened. He was withdrawn from his family and community long before the attack, and he had hardly left home.

A week before the attack, Mr. Rudakubana tried to travel to his former high school, the police said, but his father ran out of the house and begged the taxi driver not to drive him. Eventually, the teenager returned to the house.

Still, on July 29, he managed to travel by taxi to Hart Space, where a sold-out Taylor Swift-themed dance class for 6- to 11-year-olds was being held during the school’s summer break.

Mr. Rudakubana rampaged through a room full of 26 children, stabbing several of them. The injuries sustained by Bebe King, 6, and Elsie Dot Stancombe, 7, were so severe that they died inside the building, police said, and Alice da Silva Aguiar, 9, ran outside with the other children but soon collapsed. She was taken to the hospital and died the next day. Another eight children and two adults were wounded in the attack.

The case has raised questions about how authorities may have missed an opportunity to stop the violence before it started. The government said it would hold a public inquiry into the case to better understand what happened and what needs to change. But the case also highlighted the problem of young people fixated on extreme violence gaining access to online images and messages that fuel that obsession.