PORCUPINE, S.D. - A 20-year-old Porcupine, South Dakota man has been sentenced to 12 years in federal prison for the shooting death of his pregnant girlfriend. McKenzie Big Crow was convicted of Involuntary Manslaughter, the Unborn Victims of Violence Act, and Possession of an Unregistered Firearm.

On Aug. 20, 2023, Big Crow was illegally in possession of a Savage Arms Model 62 semiautomatic rifle. Prosecutors say the barrel had been sawed off, and the defendant had taped parts of an Airsoft rifle to the gun to make it look like an AK-47.

Big Crow told investigators he had placed the gun inside a backpack, and it discharged when he bumped the bag against a door. The bullet struck 19-year-old Ashton Provost in the chest, killing her and her unborn child within minutes. The gun was later found hidden under Big Crow’s bed.

On the day of the shooting near Porcupine, Big Crow had several drugs in his system, including marijuana, cocaine, ecstasy and methamphetamine.

“We commend the U.S. Attorney’s Office in the District of South Dakota for its decision to pursue charges under the Unborn Victims of Violence Act — recognizing the value of every life lost as a result of this crime,” said Special Agent in Charge Alvin M. Winston Sr. of the FBI Minneapolis. “This case highlights our shared commitment to justice for the most vulnerable and to holding violent offenders accountable to the fullest extent of the law.”

Big Crow was indicted by a federal grand jury in June 2024 and found guilty by a jury in Jan. 2025.