Double homicide defendant Anthony Casillas, 22,  is facing additional charges — accused of beating a detention officer unconscious Saturday, according to the Curry County Sheriff’s Office.

Deputies were called to the Curry County Adult Detention Center around 11:30 p.m.

Undersheriff Wesley Waller said the detention officer was punched in the face and knocked unconscious by Casillas, who then locked himself in his cell following the attack.

Waller said the detention officer, who he declined to identify, was treated at the Plains Regional Medical Center emergency room for a serious head injury.

Waller said the assault is still under investigation and deputies are conducting interviews.

Charges had not been filed against Casillas as of Monday.

Casillas is in jail awaiting trial on two counts of first-degree murder. He is accused of the Sept. 25 shooting deaths of 52-year-old Gary Payne of Melrose and 36-year-old Melissa Ward of Lubbock.

County administration said the detention officer’s condition has improved and he is awaiting a doctor’s release to return to duty.