Seyoum Mesfin, Ethiopia’s long-serving former foreign minister, was one of the foremost African diplomats of his generation. He was gunned down this month in Tigray by the armed forces of a lesser man – Abiy Ahmed, Ethiopia’s prime minister and Nobel peace prize winner. Some suggest it was the Eritrean military, Abiy’s allies, who killed Seyoum, although their presence in Tigray is officially denied. The circumstances of his death remain murky....