Police in Ethiopia said they had discovered a mass grave with 200 bodies near the border between Somalia and Oromi in the country.
Hundreds of thousands of people were displaced by violence in the past year.
Local media reported that the tomb was found during an investigation of alleged atrocities committed by the former president of the Somali region in Ethiopia.
Abdi Mohammed waits for lawsuits against allegations of ethnic clashes.
The well-known regional security force known as the Liyan police is accused of carrying out murders in the Somali and Oromi region and reported directly to the local president.
Police are trying to identify 200 found bodies.
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Mr Mohammed was forced to resign in August, and was arrested a few weeks after he broke out in the regional capital of Jijiga.
He is supposed to oversee extensive violations of rights including torture, rape and killing during the 13-year government.
Last month, state broadcaster Fano announced that he had tried to escape police custody by climbing through the window in court.