The terror suspect accused of stabbing Sir David Amess to death showed an interest in radical Islam and was referred to the Prevent programme after finishing school, it is alleged. Police and MI5 are said to be mystified about why the veteran Tory politician was singled out for attack by a suspected Islamic extremist. Ali Harbi Ali, 25, was referred to Prevent, the Government's counter-terrorism programme, several years ago – but his behaviour was not considered to be extreme enough to alert MI5. His referral is understood to have coincided with a deterioration in his relationship with his Somali-born parents. Born in Southwark to a family described as 'high class' in Somalia, Ali grew up in a three-bed 1980s terrace house in Croydon with his mother, two sisters and younger brother. His parents split up when he was young and his father returned to Somalia. One neighbour, who has known the family for 20 years, said Ali spoke of hopes of becoming a doctor. 'He told me he'd been doing exams and he seemed westernised,' the neighbour said. But after finishing school, Ali is alleged to have shown an interest in radical Islam and was referred to the Prevent programme. He decided to move in with an aunt and her sons in a council house in the upmarket north London enclave of Kentish Town, in a street of £2 million three-storey townhouses. MP Mark Francois lays flowers at the scene near Belfairs Methodist Church in Eastwood Road North Candles are lit next to a portrait of David Amess during a vigil for him at St Michaels Church, in Leigh-on-Sea People look at flowers left by the police cordon nearby the Belfairs Methodist Church As police continued to quiz the London-born suspect, his father spoke of the family's shock. Harbi Ali Kullane, a former media and communications adviser to the Prime Minister of Somalia, said he was 'traumatised' by his son's arrest. He added: 'At this particular moment we are going through [an] unprecedented and horrific situation.' Shock: Harbi Ali Kullane, who was a Somali government adviser Mr Kullane spoke out as details emerged about the suspected killer's upbringing in south London. Detectives have been piecing together the suspect's movements in the hours before Friday's attack. They have not found any obvious affiliation to a terrorist group and do not believe Ali had ever previously met Sir David. They have found nothing to suggest the MP was attacked because of his voting record, 'but that could well come out as a factor', a source said. Police upgraded the attack to a terrorism incident on Friday night after interviewing the suspect. Officers spent the weekend searching his home and yesterday erected a forensic tent in the front garden. Others were seen walking inside holding shovels, suggesting the rear garden was being dug up. CCTV footage from nearby convenience stores has been seized by police, suggesting Ali walked past them to reach the nearby Gospel Oak station to travel to Sir David's constituency surgery at the Belfairs Methodist Church in Leigh-on-Sea, Essex, on Friday morning. One neighbour told how armed police swooped on the suspect's north London home hours after the attack. 'They all arrived in the early afternoon – it was very dramatic,' he said. 'It's absolutely horrifying to think the property is linked to the MP murder. They've been here ever since doing a lot of work.' Another neighbour described the household as 'polite, respectful and decent'. He said: 'There was often a tallish chap outside who would be around 25. He would smoke outside. He'd always say hello. 'They're a good family. This is off the scale. It's horrendous. 'They were all great. I can't believe it. They were polite and respectful. 'It's very shocking that he may have travelled from this street to reach the MP's constituency. It's incredible.' Mr Kullane returned to the UK two years ago to have a heart operation on the NHS, neighbours said. He lives with his sister in the north London district of Bounds Green, and the home was also visited by police over the weekend. Police also searched the Croydon house where the suspect's mother and siblings live. Officers spent more than 24 hours scouring the premises and took the family away, with police warning them that they would not be returning for a while. A neighbour, who asked not to be named, said: 'The kids used to go to a mosque nearby, but I didn't think they did any more. They've been very good neighbours.' All rights reserved for this news site (dailymail) and under his responsibility