A police investigation into the Southport attack is still active, a senior officer has said.
Rudakubana murdered three girls at a Taylor Swift-themed dance class last summer in the Merseyside town, when he was 17 years old.
He was sentenced to a minimum of 52 years behind bars after pleading guilty to killing Alice da Silva Aguiar, nine, Bebe King, six, and Elsie Dot Stancombe, seven, in July.
Merseyside Police’s detective chief inspector Jason Pye told Sky News’ national correspondent Tom Parmenter police have been unable to establish that Rudakubana followed any ideology, only that he was “obsessed with violence of all kinds”.
“All of the evidence that we found in relation to him shows that he was obsessed with violence,” he said.
“The planning shows that he was intent that day on going out to commit mass murder and everything else that we found shows that he has a real intent for violence.
“I suppose what we don’t know, because we’ve never found it, is the ideology. That’s just not there.”
He added police also found no evidence to indicate anyone else had played a role in radicalising the now 18-year-old.
“It was more a suggestion that he was probably more socially isolated than being radicalised by anybody,” he said.
Following a clip showing Rudakubana’s father trying to stop his son from entering a taxi which was going to head towards a high school the week before, the officer was asked what the input from the killer’s immediate family had been in the investigation.
“We still have a live investigation ongoing. So I’m unable to answer any questions in relation to the parents at this stage,” Det Chf Insp Pye said.
When pressed on what that meant, the officer added: “We have a live investigation ongoing, and that is something that we are still looking into.”
However, the officer said Rudakubana had made “disturbing” comments about his victims when he was overheard talking while in custody.
“The words that he said were really disrespectful to the families and those three little children,” he said.
“Very distasteful. It’s some of the worst things that I think I’ve ever heard as a detective.”
One of the country’s most senior counterterrorism officers, meanwhile, said that although the absence of an obvious motivation meant the killings had not met the legal definition of terrorism, “that does not make the horrendous acts any less terrifying or terrorising”.
Deputy assistant commissioner Vicki Evans, senior national co-ordinator for Counter Terrorism Policing, said: “The full weight of our collective investigative teams and the criminal justice system has been brought to bear to deliver this conviction.”