PESHAWAR      -        A police constable was shot dead by an unknown assailant when he was on his way home after performing duty in the vicinity of Tangi police station on Thursday. Police said, constable, Zar Mast Khan, who was on night duty at the Excise Office Charsadda, was shot dead by an unknown armed man while returning from duty. The body of the deceased was shifted to Tangi Hospital for medico-legal formalities while police have launched a search operation in the area to nab the assailant.