United States Attorney Alison J. Ramsdell announced the sentencing of Daryl John Plumman, a 32-year-old man from Parmelee, South Dakota. U.S. District Judge Eric C. Schulte sentenced Plumman to four years and nine months in federal prison for assaulting a fellow jail inmate and possessing a firearm as a felon. Following his prison term, Plumman will undergo three years of supervised release and pay a $200 special assessment to the Federal Crime Victims Fund.

Plumman was indicted by a federal grand jury in September 2023 and pleaded guilty on July 24, 2024. The charges are linked to two incidents on the Rosebud Sioux Indian Reservation in 2023.

On April 21, 2023, law enforcement sought Plumman in connection with an alleged assault earlier that day. He was found sitting in the driver's seat of a parked vehicle with a loaded 9 mm pistol under his seat. Due to his previous conviction for abusive sexual contact in federal court, it is illegal for him to possess firearms or ammunition.

On July 29, 2023, while incarcerated at the Rosebud Sioux Tribe Adult Correctional Facility, Plumman and another individual attacked an inmate using a pencil as a weapon.

The U.S. Attorney’s Office prosecuted the assault case under the Major Crimes Act, which requires certain violent crimes occurring in Indian Country to be tried federally rather than at the state level.

The investigation was conducted by Rosebud Sioux Tribe Law Enforcement Services and the Bureau of Alcohol, Tobacco, Firearms and Explosives. Assistant U.S. Attorneys Kirk Albertson and Brian Murphy handled prosecution duties.

Following sentencing, Plumman was remanded into custody by the U.S. Marshals Service.