The Intelligence and Security Committee (ISC) is investigating the events leading up to the murder including the actions of the intelligence and security agencies and police counter-terrorism. Andrew Parker, the Director General of MI5, has said that knowing an individual does not necessarily mean the agencies knew everything about them, adding: "Being on our radar does not necessarily mean being under our microscope."
He added: "We only focus the most intense intrusive attention on a small number of cases at any one time. The challenge, therefore, concerns making choices between multiple and competing demands to give us the best chance of being in the right place at the right time to prevent terrorism."
Raffaello Pantucci, of the Royal United Services Institute, said they would not have "trip wires" that often expose deadly plots, adding that a lot of people appear on the periphery of intelligence-led investigations.