Gradyn Blue Arm, a 27-year-old man from Dupree, South Dakota, was sentenced on July 13 to 12 years in federal prison after being convicted of voluntary manslaughter. The sentencing was announced by United States Attorney Ron Parsons and took place before U.S. District Judge Eric C. Schulte.
Blue Arm will also serve three years of supervised release and must pay a $100 special assessment to the Federal Crime Victims Fund. He was indicted in September 2025 and pleaded guilty on April 9, 2026.
The conviction is related to an incident that occurred on June 3, 2025, within the Cheyenne River Sioux Indian Reservation. After being asked to leave a residence in Dupree, Blue Arm returned armed with knives and argued with the victim and others outside the home. He then walked away but was followed by the victim and two other individuals; soon after, Blue Arm stabbed the victim in the abdomen with a knife, resulting in death.
This case fell under federal jurisdiction due to the Major Crimes Act, which requires certain violent crimes occurring in Indian country be prosecuted federally rather than at the state level. The case was investigated by both the FBI and Cheyenne River Sioux Tribe Law Enforcement Services. Assistant U.S. Attorney Wayne Venhuizen prosecuted it.
Blue Arm was immediately remanded into custody of the U.S. Marshals Service following sentencing.
The U.S. Attorney for the District of South Dakota is responsible for enforcing federal laws across its district as well as handling criminal prosecutions and civil cases; it serves as chief federal law enforcement office for South Dakota while supporting initiatives aimed at improving public safety and quality of life, according to its official website.