Native American activist Leonard Peltier, who was convicted of killing two FBI agents on a South Dakota reservation 50 years ago, was released from prison on Tuesday after former President Joe Biden commuted his life sentence.

Peltier, 80, is now free to return to his reservation in North Dakota to spend his remaining years confined in his home.

In June 1975, Peltier murdered FBI agents Jack Coler and Ronald Williams on the Pine Ridge Indian Reservation in South Dakota. According to FBI files, the agents traveled there to serve arrest warrants for robbery and assault with a dangerous weapon to other suspects.

Though he had an outstanding warrant for unlawful flight to avoid prosecution and attempted murder of an off-duty police officer, the agents were unaware Peltier was present on the reservation. Coler and Williams were found dead after a shootout. They were killed at close range.

Peltier was identified as the only person in possession of an AR-15 rifle that could fire a .223 bullet linked to the murders, according to witnesses.

The man was then arrested in February 1976, convicted in April 1977 on two counts of first-degree murder, and sentenced in June that year to two consecutive life terms. He received an additional five-year sentence after a failed prison escape.

In a 60 Minutes interview that aired in September 1991, Peltier admitted he was involved in the shootout that killed the two agents. However, he has maintained his innocence in killing them.

Peltier’s supporters celebrated his anticipated release, believing he was unjustly imprisoned as a Native American for the agents’ deaths.

“We made a commitment to free Leonard Peltier and bring him back to his homelands – this is us fulfilling that commitment,” said Nick Tilsen, founder and CEO of Native American activist organization NDN Collective. The group will host a celebration on Wednesday for Peltier in Belcourt, N.D.

On his last day in office, Biden commuted Peltier’s lifelong sentence over concerns of the inmate’s old age and poor health. The clemency action came in opposition to then-FBI Director Christopher Wray, who said Peltier was a “remorseless killer” and shouldn’t be freed.

“Granting Peltier any relief from his conviction or sentence is wholly unjustified and would be an affront to the rule of law,” Wray wrote in a letter to Biden.

Wray previously opposed Peltier’s request to be released on parole, which was denied last year.

The FBI Agents Association, which represents more than 14,000 current and retired special agents, sharply criticized Biden’s commutation of Peltier’s sentence.

“This last-second, disgraceful act by then-President Biden, which does not change Peltier’s guilt but does release him from prison, is cowardly and lacks accountability. It is a cruel betrayal to the families and colleagues of these fallen Agents and is a slap in the face of law enforcement,” said Natalie Bara, president of the group.

“Leonard Peltier has never expressed remorse for his actions. Special Agents Coler and Williams were stolen from their families, robbed of the chance to share precious time and milestones with their loved ones. Leonard Peltier should not have been granted a mercy he so cruelly denied to the Coler and Williams families.”