The hunt for Saddam Hussein's inner circle claimed its biggest success so far last night when American military officials announced the arrest of Mohammed Hamza al-Zubaidi, a former Iraqi prime minister who was implicated in the suppression of Shia uprisings after the 1991 Gulf war. Mr Zubaidi, accused of masterminding the slaughter of thousands of Marsh Arabs, was seized at about 9.30pm local time at a house in Hillah, 56 miles south of Baghdad, by a brigade of fighters affiliated to the Iraqi National Congress (INC), working with American special forces. A former member of the Iraqi revolutionary command council,...