President Biden commuted the prison sentence of Leonard Peltier, an imprisoned Native American rights activist, using his final minutes of presidential power on Monday to free a man who has spent nearly 50 years in federal prison after he was convicted of murder in connection with the killing of two F.B.I. agents.

In the final hours of President Joe Biden’s term, he granted Leonard Peltier clemency through commutation, allowing him to serve his life sentence at home on the Turtle Mountain Indian Reservation in North Dakota.