Police searching for a motive for the mass stabbings in Southport that left three children dead are increasingly focusing on the state of their suspect’s mental health or potential neurodivergence in the years before the attack, the Guardian understands. A British-born 17-year-old was arrested after a Taylor Swift-themed dance class in the Merseyside seaside town was plunged into horror, with 11 children and two adults stabbed. Five children remain in a critical condition, as do the two adults believed by police to have been wounded as they tried to shield the primary school-age children from the rampage just before midday on Monday. The 17-year-old, arrested on suspicion of murder and attempted murder, is still in custody as police carry out forensic searches at a house in the village of Banks that he travelled from, and on the taxi in which he travelled to the scene. The criminal investigation by Merseyside police has multiple strands, the motive for attacking such a soft target being a key one. Detectives are looking for and studying any material held by statutory agencies such as educational institutions, health or social services, about the suspect and any concerns raised, for instance about his behaviour, when younger. In the Commons, Yvette Cooper called for police to be given time to carry out the criminal investigation. “There will be wider questions for other days,” the home secretary said. Police say terrorism is not a motive, but caveat this by saying that is their view “at this stage”. Searches of electronic devices such as phones and laptops linked to the teenage suspect continue, and investigators will gain greater confidence that no terrorist or ideological motive played a part, once those searches are completed. It is understood that nothing supporting any kind of terrorist motive has been found so far. Police are looking for any explanation as to why the suspect targeted the dance class for young girls during the school summer holiday. In law, any mental health or neurodivergence, such as autism, do not necessarily protect a suspect from criminal charges, prosecution and conviction. Merseyside police have said there is no evidence of terrorism and “we are not looking for anyone else in connection with it [the attacks]”, leaving the community still searching for answers for what could have motivated the teenager to carry out such a callous and ferocious attack. Footage captured from a house in Banks shows a man pacing repeatedly back and forth outside a property that was later cordoned off by police. The man is wearing a green hoodie and a Covid-style face mask. In the village of Banks, in the wake of Monday’s incident, nobody said they really knew the teenager, or recalled ever seeing him there. They did know the older couple, believed to be his parents, who live at the house. Some who knew of the family said they largely kept to themselves, but the local community had previously rallied round with a fundraiser to support them in a charitable appeal. They had moved to Merseyside from south Wales in about 2013, and lived in a house in the centre of the seaside resort, before moving out to Banks, a village in Lancashire about five miles from Southport. The teenager’s father had trained in karate for many years, and he also studied the martial art as a boy in Wales. However, those involved in the sport in Merseyside do not ever recall the boy participating once the family moved to England. His former neighbours in Cardiff said they were a “nice family”, adding they were “shocked” to learn of the arrest. Sensei Chico Mbakwe, 79, who had taught the boy karate at St Cadoc’s church hall in Llanrumney said he was a “typical, normal five-year-old” who continued to train at the dojo even after his father fell out with club leaders. Mbakwe said: “He was a good child, a normal child, who had lots of energy. “I remember him because he continued to train with us for around three months after his father left for another dojo I own.” Mbakwe added: “The dad was just a pleasant, normal guy, and the son was just a normal five-year-old. “Children don’t tend to stand out that much at that age, but I do remember him. They’re all daft as cabbages. “I’m sad to hear what has happened. It makes me worry about my grandchildren and great-grandchildren with all the knife crime around these days.” Former neighbours in the Cardiff suburb of Thornhill, where the family also lived briefly, said the boy and his brother were “nice enough” and always “bouncing off the walls”. “We talked over the fence round the back, the kids went to school,” one said. “They were nice children – they were boys at the age where they were bouncing off the walls. Always running around screaming and playing football in the garden, that kind of thing. “They were boisterous boys. I got on really well with them.”