Browning man sentenced for murder and kidnapping MTN News and last updated 2021-07-21 19:08:14-04 GREAT FALLS â Jason Avery Mattson of Browning, who admitted murdering a man and then holding a woman hostage at knife-point, was sentenced in federal court in Great Falls on Wednesday. Mattson, 30 years old, pleaded guilty on March 30 to second degree murder and to kidnapping as charged in an indictment. Prosecutors said that on March 3, 2020, law enforcement officers were called to a clearing near Cut Bank Creek, near the Boarding School community on the Blackfeet Indian Reservation, after a body was found. The body was identified as "John Doe" and family was notified of his death. An autopsy confirmed the manner of death as homicide and determined that Doe sustained blunt force injury to his back and extremities and that there was evidence on the neck consistent with strangulation or blunt force injury.