Tianna Leaf Arellano Sentenced in Rosebud Knife Attack

A Rosebud woman who stabbed a family member multiple times in a violent Christmas Day aftermath was sentenced to 25 months in federal prison. Tianna Leaf Arellano, 30, launched the attack on the morning of December 26, 2015, at a relative’s home south of Mission, South Dakota, plunging a knife into the victim’s abdomen with enough force to lacerate the liver and cause life-threatening internal injuries.

Arellano was indicted by a federal grand jury on February 17, 2016, on two counts: Assault With a Dangerous Weapon and Assault Resulting in Serious Bodily Injury. On August 3, 2016, she pleaded guilty to the first count, leaving the more serious charge to be dropped as part of a plea agreement. U.S. District Judge Roberto A. Lange handed down the sentence on October 24, 2016, ordering 25 months in federal custody, followed by three years of supervised release and a $100 special assessment to the Federal Crime Victims Fund.

The attack erupted during a heated argument between Arellano and the victim, another family member, inside the home. Witnesses told investigators that the confrontation escalated rapidly when Arellano seized a knife and began stabbing the victim repeatedly. Emergency responders rushed the injured person to a hospital in Valentine, Nebraska, before Life Flight airlifted them to Rapid City Regional Hospital for emergency surgery and extended care.

Though the victim survived, the physical and emotional scars remain. Medical reports detailed multiple penetrating wounds and internal trauma, requiring extensive hospitalization and follow-up treatment. Federal prosecutors emphasized the brutality of the assault, noting the use of a deadly weapon in a domestic setting elevated the case to federal jurisdiction under Indian Country laws.

The Rosebud Sioux Tribe Law Enforcement Services led the investigation, working closely with federal authorities to secure evidence and witness statements. Assistant U.S. Attorney Kirk W. Albertson prosecuted the case, arguing for a substantial sentence given the violent nature of the offense. Arellano was taken into custody immediately after sentencing by the U.S. Marshals Service.

Tianna Leaf Arellano’s conviction underscores the federal government’s continued push to address violent crime in tribal communities. With jurisdiction often overlapping between tribal, state, and federal agencies, cases like this highlight the complexity—and urgency—of delivering justice in Indian Country. Her prison term marks a step toward accountability, but for many, it also serves as a grim reminder of the violence that can erupt behind closed doors.