In the United States, there are federal laws, and there are state laws. And it's state law that prohibits felony acts such as murder, rape, burglary, aggravated assault, and larceny.
But the state does not have jurisdiction in Indian Country. And so if a tribal member on a reservation commits a major crime, he or she is prosecuted by the federal government.
It's a unique situation. Indigenous people, members of tribes, are commonly tried in federal court for state crimes, while other racial or ethnic groups are not.