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.

The president commuted Peltier over the objection of former FBI Director Christopher Wray. In a private letter sent to Biden earlier this month and obtained by The Associated Press, Wray reiterated his position that “Peltier is a remorseless killer,” and urged the president not to act.