The son of an Islamist opposition leader in Sudan said his father was released after being held for six weeks in detention without charges. Hassan Turabi was sent home from an eastern Sudanese prison at dawn on Monday. His son, Siddique Turbai, said his deteriorating health was a factor in the release. The 76-year-old Turabi is a leading Islamic fundamentalist ideologue. He was once an ally of President Omar al-Bashir and was behind the president's rise to power in a military coup in 1989. The two fell out in 1999, and Turabi set up his own party. Turabi was arrested in mid-January after telling reporters al-Bashir should give himself up to the international tribunal that is seeking his arrest for war crimes in Darfur.