The man who killed Saskia Jones and Jack Merritt was a convicted terrorist who had spent eight years in prison. Usman Khan was jailed in 2012 for preparing acts of terrorism. While he was inside he underwent a deradicalisation programme. He was released on licence last December and on Friday he travelled to London to take part in a conference on prisoner rehabilitation. It was there that Jack and Saskia were murdered. We speak to the BBC’s Home Affairs correspondent Dominic Casciani about Usman Khan and to Hanif Qadir, a former jihadist who has worked to de-radicalise extremists.

Presenter: Matthew Price