JACKSON, Miss. (AP) — One inmate has pleaded guilty to participating in a deadly prison riot in Mississippi while a second prisoner has been charged in the case.

One guard was killed and 20 people were injured in the May 20 riot at the privately-run Adams County Correctional Facility in Natchez, which holds illegal immigrants convicted of crimes in the U.S.

Yoany Oriel Serrano-Bejarano was charged Tuesday. A complaint filed by an FBI agent says he assaulted a guard and helped other inmates climb onto the roof of a building where correction officer Catlin Carithers was beaten to death.

Serrano-Bejarano is at least the second inmate charged in the case. Juan Lopez-Fuentes pleaded guilty Aug. 27 in U.S. District Court in Natchez. He faces up to 10 years in prison at sentencing Nov. 19.