Cody Ben Zephier, age 21, of Kenel, South Dakota, was found guilty by a federal jury of Assault of a Dating Partner by Strangulation, Assault of a Dating Partner Resulting in Substantial Bodily Injury, and Assault by Striking, Beating and Wounding after a three-day trial in Aberdeen. The verdict was returned on July 29 following the proceedings in federal district court.
According to United States Attorney Ron Parsons, these convictions carry potential penalties totaling up to 16 years in prison, three years of supervised release, $600,000 in fines, and a mandatory $225 special assessment. Restitution may also be ordered. Zephier had been indicted by a federal grand jury in August 2025.
The incident occurred during the early morning hours of June 27, 2025, at Zephier’s home within the Standing Rock Sioux Indian Reservation. After an argument with his live-in girlfriend escalated when she slapped him across the back as he walked away, Zephier threw her to the floor before punching her with “hammer fists,” kicking her and choking her until she could not breathe. He then called 911 because he could not stop himself from “smacking” his girlfriend or from her bleeding. The victim suffered two broken wrists and extensive bruising to her face and neck as a result.
The U.S. Attorney’s Office prosecuted this case under the Major Crimes Act—a federal statute requiring that certain violent crimes occurring in Indian country be prosecuted federally rather than at the state level. The Bureau of Indian Affairs investigated the matter while Assistant U.S. Attorney Carl Thunem led prosecution efforts.
A presentence investigation has been ordered for Zephier; sentencing has not yet been scheduled and he remains in custody pending further proceedings. The U.S. Attorney for the District of South Dakota is responsible for enforcing federal laws across its jurisdiction and advancing community safety through criminal prosecutions and civil cases as part of its mandate as chief law enforcement office for its district, according to the official website.