Every night, for weeks at a time last year, Saad al-Mukhtar put a small group of people in the back of his sports utility vehicle and drove them under the cover of darkness from his home in the Sudanese city of Geneina across the border and into Chad.
The operation was an extraordinary act of bravery and selflessness: Mukhtar is an Arab, and the people he was smuggling to safety were members of the darker skinned Masalit community who were being targeted in a vicious wave of ethnic violence perpetrated by Arab militias.
