Sudan’s former president Omar Hassan al-Bashir sits inside a cage at the courthouse where he is facing corruption charges.

Sudan’s public prosecutor said Monday a mass grave has been discovered east of the capital Khartoum, allegedly containing students killed in 1998 who tried escaping military service.

An investigation has been launched, the prosecutor said, adding that some of the suspected killers belonging to the ousted administration of Omar al-Bashir had fled.