CHEYENNE, Wyo. (AP) – An Indian tribe will get a chance to argue the state of Wyoming never should have prosecuted a member in the beating death of his baby daughter because the attack happened in an area the tribe claims is still legally part of the Wind River Indian Reservation.

The 10th Circuit Court of Appeals in Denver has approved the request by the Northern Arapaho Tribe to file a friend of the court brief in support of Andrew Yellowbear Jr.’s appeal.

Yellowbear is serving a life sentence in state prison in the 2004 beating death of 22-month-old Marcela Hope Yellowbear.

The girl was pronounced dead at a Riverton hospital after her mother, Macalia Blackburn, took her there with a variety of injuries, including broken bones, severe burns and cuts and bruises to most of her body.

Blackburn was sentenced to 60 years in prison after pleading guilty in state court to being an accessory to second-degree murder.

Yellowbear maintains the state lacked authority to prosecute him because his family home in Riverton was in “Indian Country.” The tribe supports Yellowbear’s jurisdictional argument that any prosecution of him should occur in tribal or federal court.

The appeals of the tribe and Yellowbear both focus on a 1905 act of Congress that opened reservation land around Riverton to settlement by non-tribal members.

The state maintains the act removed the land’s legal status as part of the Wind River Indian Reservation, but the tribe and Yellowbear hold it did not.

The Wyoming Supreme Court and U.S. District Judge Clarence Brimmer of Cheyenne previously upheld Yellowbear’s conviction.

The Wyoming attorney general’s office had opposed the tribe’s request to enter the case. Attorney General Bruce Salzburg declined comment on the Jan. 14 appeals court decision.

The tribe issued a statement emphasizing that it’s not seeking to defend Yellowbear by entering his case and only wants to protect its interests in the boundary dispute.

“The tribe must protect the reservation boundary, whether it arises as an issue in Yellowbear’s case or some other context,” Ronnie Oldman, a member of the Northern Arapaho Business Council, said in the statement.

Lawyer Jim Drummond, who represents Yellowbear, said there’s a long, mixed history of court rulings about the legal status of land around Riverton that should be cleared up.

“It’s our position of course that there was no disestablishment – they opened up the lands, but they did not disestablish its Indian Country character,” Drummond said.