Hassan al-Turabi was a Sudanese politician, scholar and De facto leader. He was the alleged architect of the 1989 Sudanese military coup that overthrew Sadiq al-Mahdi and installed Omar al-Bashir as president. He has been called "one of the most influential figures in modern Sudanese politics" and a "longtime hard-line ideological leader". He was instrumental in institutionalizing Sharia in the northern part of the country and was frequently imprisoned in Sudan, but these "periods of detention" were "interspersed with periods of high political office".