Ethiopian police say they have discovered a massive tomb with 200 authorities at the border between Somalia and Oromia.
In recent years, hundreds of thousands of people have been displaced by violence.
Local media reported that the grave was found during a probe on alleged thefts by a former president of the Ethiopian Somali region.
Abdi Mohammed is awaiting trial for allegations he contributed to ethnic clashes.
The famous regional security force, known as Liyu Police, is accused of murdering the area between Somalia and Oromia regions, and it was communicated directly to the regional president.
The police are trying to identify the 200 found bodies.
Mr Mohammed was forced to step down in August and was arrested weeks after the violence in the region's capital, Jijiga.
It is alleged that because of his 13-year rule, widespread abuse of rights, including torture, rape and murder, has been monitored.
#Ethiopia: The former # Somali Chief Administrator of the region accused of trying to escape from prison https://t.co/vu279IAojc pic.twitter.com/LFvhqxzeUo
– FANA BROADCASTING C (@fanatelevision) October 19, 2018
Fana, a nationwide broadcaster last month, reported that he was trying to avoid police detention, climbing the window before proceeding.