Zareb Osman remembers the night in 2010 that he decided to leave for Israel. It was the night the then 21-year-old student at Al-Neelain University, Sudan, had been standing blindfolded in a thickly wooded patch north of Khartoum. This is how it all ends, he had thought. After putting the fear of execution into him, Osman’s captors untied his hands behind his back. They gave him two choices: return to campus and resume his studies but join the student wing of the ruling National Congress Party. Or continue secretly supporting the opposition Communist Party, get arrested again and be brought back to this ‘same place’ for them to finish off the job.

Osman wasn’t sure exactly where this ‘same place’ was. But it was where he had spent the last three months being starved, having his fingernails pulled out and plastic burnt into his flesh. ‘They picked me up because of who I was,’ he says. The aspiring civil engineer belongs to the Gimir tribe of South Darfur. In 2010 Sudan was still reeling from the most intense period of sectarian conflict in Darfur, which had led to 400,000 dead, three million displaced and an international arrest warrant against President al-Bashir for crimes against humanity. That summer Osman and a few other students – all of them from the war-torn regions of Darfur or the Nuba Mountains – were detained after turning up to a campus seminar on the crisis.