Hadith.5255 - Al-Husayn ibn Sa'id narrated from Fadalah, from Aban, from Zurara, from Abu Abdullah عليه السلام who said: "Whoever was granted protection (dhimmah) by Messenger of Allah سبحانه وتعالى (peace be upon him and his family), his blood money (diyyah) is complete (to that of a muslim)."
Zurara commented: "These are the people about whom Abu Abdullah عليه السلام spoke, referring to those whom the Prophet صلى الله عليه وعلى آله وسلم granted protection."
Furthermore, whoever opposes the Imam by intentionally killing one of these protected individuals deserves capital punishment - not because of the sanctity of the dhimmi himself but due to the transgression against the authority of the Muslim leader.