DERA ISMAIL KHAN: Unidentified armed men martyred a police cop at his home in Kulachi tehsil in the district on Sunday, sources said. The sources said that wireless operator constable Mohammad Jamil was killed at his home. The cop was deputed at the Takwar police post in Kulachi tehsil. Someone knocked at the door when he reached home. He was killed as soon as he opened the door and came out of his residence. He died on the spot.