Eighteen-year-old Mazin Mardan was the third employee of the Al-Mousiliyah sattelite channel in Mosul to be killed by insurgents.A Mosul police commander described Sunday’s shooting but refused to discuss possible motives.A hospital official in the city confirmed the slaying.Both spoke on condition of anonymity because they were not authorized to brief the media.Mosul is Iraq’s third largest city and a former Al-Qaeda enclave.According to Reporters Without Borders, at least 230 media workers have been killed in Iraq since 2003.