Prosecutors say 32-year-old Jeremiah Burns entered his plea Friday.
Under the terms of his plea agreement, Burns will be sentenced to 20 months in federal prison followed by a term of supervised release to be determined by the court.
Burns' sentencing hearing has yet to be scheduled.
He was arrested in August in connection with the fatal crash that occurred on the Jicarilla Apache Nation on Oct. 22, 2011.
Prosecutors say Burns was driving under the influence of alcohol and marijuana which rendered him incapable of exercising clear judgment and a steady hand in handling a vehicle.