Counter-terrorism detectives are investigating whether David Amess was specifically targeted for attack by a man who stabbed the MP multiple times, then waited for police to arrest him. Sources confirmed the suspect was Ali Harbi Ali, 25, who on Saturday was detained under terrorism laws with a magistrate authorising his detention until next Friday. The atrocity was assessed by senior counter-terrorism officials as being linked to a jihadist ideology because of developments in the investigation after the suspect was arrested, the Guardian understands. These include statements the suspect allegedly made after police detained him. The suspected terrorist attack just after midday on Friday, at the constituency surgery of the backbencher for Southend West, has stunned Westminster and forced a review of MPs’ security. Specialist counter-terrorism lawyers with expertise in bringing terrorist prosecutions have been discussing the investigation with detectives from Scotland Yard’s counter-terrorism command, who are leading the investigation. The Guardian has revealed the suspect was previously known to the Prevent scheme, the official programme to stop radicalisation. His involvement was short, according to multiple sources. He has no known previous terrorist involvement. The suspect remained in custody having been first arrested on suspicion of murder at the scene, a Methodist church in Leigh-on-Sea, Essex. Despite the gap between the attack and the suspect’s arrest minutes later by police, no one else was injured, nor have witnesses or police described any attempt to stab anyone else. Electronic devices are being examined, and police have said two addresses in London were being searched as part of the inquiry. Police have said they are looking for no one else in relation to the killing of the MP, and that a knife was recovered at the scene. In a statement, the Crown Prosecution Service said lawyers from its Special Crime and Counter Terrorism Division were assisting police: “The CPS is supporting the police in their investigation into the appalling event which led to the tragic death of Sir David Amess.” Amess was so badly injured that he died at the scene. Southend borough councillor John Lamb said: “This person had gone there to join the surgery and when he got the chance he went in to be seen by David, then he drew a knife and stabbed him. “We knew it must be very serious because the paramedics had been working on Sir David for over two and a half hours and they hadn’t got him on the way to hospital.” In a statement, counter-terrorism police said: “As part of the fast-paced investigation, officers have attended three addresses in the London area and conducted searches. One of these searches has concluded and the others are ongoing. A postmortem examination has taken place today.” In some areas on Saturday, police provided extra patrols as MPs held advice surgeries for their constituents. Across the country, police forces will start contacting MPs to discuss their security arrangements and offer advice. One option is to have extra security at advice surgeries, provided by private guards but paid for by the taxpayer. Police are aware that MPs, up until now at least, have been very reluctant to do anything that may deter members of the public from seeking their help. Amess, 69, is the second MP to be killed in the past five years, after the murder of Jo Cox by an extreme rightwing terrorist during the campaign for the Brexit referendum in 2016. There has been at least one foiled plot targeting another MP, and lawmakers have talked of a rising tide of threat. A spokesperson for the National Police Chiefs’ Council, which represents police leaders, said on Saturday: “In light of yesterday’s tragic attack, every MP will be contacted individually … to discuss their security arrangements, and to ensure they are aware of all advice pertaining to their personal safety and security. “They will also speak to MPs about security arrangements for any events they are planning to attend in the coming days, so the appropriate advice can be provided. “We encourage MPs to immediately report any security concerns to their local police force in order to keep themselves, their staff and members of the public attending surgeries safe. Funding is available through the Independent Parliamentary Standards Authority for security needs based on threat assessments made by police.”