A police force is being investigated for its role in the management London Bridge attacker Usman Khan after his release from jail.
The Independent Office for Police Conduct (IOPC) had already begun an inquiry into the fatal shooting of Khan, from Stoke, by Metropolitan and City of London Police officers.
It will now investigate Staffordshire Police after a referral from the force.
The probe is in its “very early stages”, the IOPC added.
The watchdog’s separate investigation will examine Staffordshire Police’s contact with the convicted terrorist, 28, who was living in Stafford, prior to the attack on 29 November.
Khan was released from prison on licence in December 2018, less than halfway through a 16-year jail term following his conviction for terror offences in February 2012.
“Our separate investigation into the decisions and actions of Staffordshire Police has just begun and will be conducted alongside the investigation into the shooting,” said Sal Naseem from the IOPC.
The BBC has contacted Staffordshire Police for comment.
Cambridge University graduates Saskia Jones, 23, from Stratford-upon-Avon, Warwickshire, and Jack Merritt, 25, from Cottenham, Cambridgeshire, were killed by Khan and three others were injured during a prisoner rehabilitation event at Fishmongers’ Hall near London Bridge.
Khan, who was armed with two knives and wearing a fake suicide vest, was tackled by members of the public, including ex-offenders from the conference, before he was shot dead by police.
Reformed prisoner John Crilly, who fought the knifeman, said he was “prepared to die” to protect others.
Speaking to the BBC in 2008, Khan complained about being under suspicion, saying: “I’ve been born and bred in England, in Stoke-on-Trent in Cobridge.”
He said “all the community knows me” and that “I ain’t no terrorist”.
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