In late December 2011 a bespectacled, balding, 47-year-old Rwandan Hutu computer technician walked free after spending eleven months in the custody of the International Criminal Court in The Hague. Believed to be a senior member of the guerrilla forces accused of genocide in Rwanda’s 1994 ethnic massacres, and of a killing spree in the Congo that left several hundred dead and many others raped and tortured, Callixte Mbarushimana had evaded arrest several times. He had, however, been captured and held for several months in 2001 (but was freed for lack of evidence), then indicted by the Tribunal for Rwanda (case dropped), and later arrested again, this time in Frankfurt (released). Early in 2011 he was yet again arrested and this time charged with five counts of murder and persecution. Today he is free once more, despite the statements of twenty witnesses. An appeal against the decision by the chief prosecutor of the International Criminal Court, Luis Moreno Ocampo, has been rejected.

Mbarushimana is almost certainly guilty. But the saga of his repeated arrests and releases says much about the overwhelming difficulty of indicting those charged with war crimes, as David Scheffer makes plain in All the Missing Souls. Known to some of his friends as the ‘Ambassador to Hell’, Scheffer served