Ethiopia police say 200 bodies have been recovered near the Somali and Amoria regions of the country.
Last year hundreds of people escaped from violence.
The tomb was discovered in an investigation by the former president of Ethiopia Somalia.
Abdul Mohammed is directly facing trial over allegations of ethnic cleansing.
A notorious local security force known as Liu Police has been accused of murdering the area between Somalia and the Omymia region and reported directly to the local president.
The police are trying to identify 200 bodies found.
In August, following a riot in the local capital, Jijiga, he was forced to arrest Mohammed Nabi.
It has been alleged that the 13-year period has been misused of widespread rights, including rape, rape and murder.
Last month, a fake broker Fana had reportedly tried to escape the police custody in a window ahead of court judge.