ABERDEEN – United States Attorney Ron Parsons announced today that U.S. District Judge Charles B. Kornmann has sentenced a Wakpala, South Dakota, man convicted of Assault of an Intimate and Dating Partner by Strangulation and Suffocation and Assault Resulting in Substantial Bodily Injury to an Intimate and Dating Partner. The sentencing took place on September 22, 2026.
Mathias Kane Fast Horse, age 19, was sentenced to five years and 11 months in federal prison, followed by three years of supervised release, and ordered to pay a $200 special assessment to the Federal Crime Victims Fund.
Fast Horse was indicted by a federal grand jury in December 2025. He pleaded guilty on June 22, 2026.
On November 18, 2024, Fast Horse purposefully inhaled some household chemicals and then strangled his girlfriend until she lost consciousness. He continued by pushing, slapping, and punching her, spraining her knee. On April 14, 2025, Fast Horse punched his girlfriend’s head several times, rupturing her right ear drum. When the woman fled and took shelter in a neighbor’s home, Fast Horse gave chase, but could not break into the house. These events occurred in Wakpala within the Standing Rock Sioux Indian Reservation.
This matter was prosecuted by the U.S. Attorney’s Office because the Major Crimes Act, a federal statute, mandates that certain violent crimes alleged to have occurred in Indian Country be prosecuted in Federal Court as opposed to State Court.
This case was investigated by the Bureau of Indian Affairs. Assistant U.S. Attorney Carl Thunem prosecuted the case.
Fast Horse was remanded to the custody of the U.S. Marshals Service to serve his federal sentence.
Source: U.S. Attorney’s Office — South Dakota — U.S. Department of Justice press release.