Crow Agency resident Delbert Dean Spear admitted to stabbing a man seven times while drinking and driving with a group of people last year.
Spear, 25, pleaded guilty in U.S. District Court in Billings on Wednesday to assault with a dangerous weapon in the Oct. 6, 2012, attack.
The victim, who was not identified, was flown to Billings for medical care for stab wounds in his chest, shoulder and arm.
Assistant U.S. Attorney Lori Suek said the victim told investigators that he and a group of people, including Spear, were drinking and driving until the car ran out of gas. Everyone kept drinking until Spear and the victim started arguing.
Spear and the victim got out, and Spear came at the victim, stabbing him multiple times in the chest until the victim fell. The victim walked to a house for help.
Spear faces a maximum of 10 years in prison and a possible $250,000 fine. Senior U.S. District Judge Jack Shanstrom set sentencing for Aug. 7. Spear remains in custody.