What president was assassinated in an explosion on August 1981, and was succeeded by a man elected as the new Supreme Leader by the Assembly of Experts on 4 June 1989 at the age of 49?
Government of Mir-Hossein Mousavi (1985–89): In August 1981, President Mohammad-Ali Rajai and Prime Minister Mohammad-Javad Bahonar were assassinated in an explosion. Ali Khamenei:  Khamenei succeeded the first Supreme Leader, Ruhollah Khomeini, after Khomeini's death, being elected as the new Supreme Leader by the Assembly of Experts on 4 June 1989 at the age of 49.
President Mohammad-Ali Rajai