 Sapper Walker was shot in an apparent 'insider attack' by a member of the Afghan National Army (ANA) at Patrol Base Hazrat in the Nahr-e Saraj district of Helmand province on Monday 7 January 2013.He was working on a construction task with other military engineers from his Troop, as part of the preparations to hand the camp over to Afghan security forces, when the Afghan soldier turned his weapon on ANA and ISAF soldiers at the base.The incident resulted in a number of casualties, all of whom were extracted to the Bastion Role 3 medical facility where Sapper Walker was pronounced dead.