Ethiopia ? An Ethiopian dictator known as “the butcher of Addis Ababa” was convicted Tuesday of genocide in a rare case of an African strongman being held to account by his own country.

Mengistu Haile Mariam, who has been living in exile in Zimbabwe since 1992, was convicted in absentia after a 12-year trial. He could face the death penalty at his Dec. 28 sentencing, but Zimbabwean President Robert Mugabe said he won’t deport Mengistu if he refrains from making political statements or comments to the media.

Mengistu ruled from 1974 to 1991 after his military junta ended Emperor Haile Selassie’s reign in a bloody coup. Some experts say 150,000 university students, intellectuals and politicians were killed in a nationwide purge by Mengistu’s Marxist regime, though no one knows for sure.