The investigation into the Plymouth mass shooting has placed one police staff worker under investigation for gross misconduct, meaning they could be sacked if allegations are upheld. Jake Davison, 22, shot dead his mother, a three-year-old girl and three other people on 12 August. He used a gun he had held a licence for since 2017, which had been taken away after he got into a fight in September 2020, only to be returned by police weeks before the killings. Potential police errors are being investigated by the Independent Office for Police Conduct (IOPC), which on Wednesday said the police civilian worker had handled “Davison’s original application for a shotgun certificate in July 2017” and later made the “decision to return Mr Davison’s shotgun and shotgun certificate in July this year”. The IOPC said a police officer was under investigation for misconduct and had investigated the fight Davison got into which led to his certificate being revoked and him having to hand his gun back. The IOPC said of its investigation: “We are investigating whether they shared information appropriately with the force firearms and explosives licensing department regarding Mr Davison’s involvement in a violent offence, and whether they took appropriate steps to seize the shotgun certificate, shotgun, and ammunition from Mr Davison.” After Davison’s assault on two youths he was put on a scheme meant to divert offenders, called Pathfinder. As part of that he had to admit his guilt and agree to attend an anger management course, and after that was completed police decided he could have his gun back. The IOPC said it hoped to complete its investigation by December. In a 12-minute attack Davison first shot his mother, Maxine, at her home before going outside and killing four strangers. Sophie Martyn, three, and her 43-year-old father, Lee, were shot as they walked their dog. Davison then shot Stephen Washington, 59, and Kate Shepherd, 66, before killing himself with his own gun. Davison had consumed anti-women “incel” propaganda but police do not believe the motivation for the shootings was terrorism-related. David Ford of the IOPC said: “We still have significant investigative work to undertake but continue to make good progress with our enquiries. We are reviewing a substantial amount of information gathered from Devon and Cornwall police and elsewhere and the force has continued to cooperate fully with our independent investigation. Based on the evidence gathered so far, we have now served disciplinary notices on two individuals within the force to advise them their conduct is subject to investigation. The serving of such notices will be kept under review. “We expect to submit a final investigation report, which will set out our findings, to the coroner and Devon and Cornwall police in December.” The IOPC added that issuing disciplinary notices did not mean disciplinary proceedings would necessarily follow, but advises staff or officers they are under investigation and of the allegations they face.