Nearly three dozen members of Congress on Friday urged President Joe Biden to grant clemency to Leonard Peltier, the now-ailing 79-year-old Native American rights activist who has been in prison for nearly 50 years.

“As Members of Congress, we sign this letter with a deep commitment to the crucial role we play in upholding justice for all Americans — and to also hold our government accountable when we see a case of injustice, as demonstrated by the long incarceration of Leonard Peltier,” reads their letter to Biden, which was led by Rep. Raul Grijalva (D-Ariz.).

“We applaud your commitment to criminal justice reform and your administration’s work to address inequities in the criminal justice system and rectify the past wrongs of our government’s treatment of Native Americans,” they wrote. “We urge you to take the next step by granting Mr. Peltier executive clemency or compassionate release.”

The letter is signed by 30 House members and three senators, Bernie Sanders (I-Vt.), Brian Schatz (D-Hawaii) and Tina Smith (D-Minn.). It’s the fourth time that Democrats in Congress have publicly appealed to Biden to release Peltier since he became president.

Interestingly, for the first time, a Republican congressman has added his voice to the calls for Peltier’s release: Rep. Tim Burchett (R-Tenn.). His office did not respond to a request for comment on why he decided to join their efforts.

Here’s a copy of the letter, which, not coincidentally, comes in advance of Indigenous Peoples’ Day on Monday.

Peltier, a longtime Indigenous rights activist, has been in prison since 1977 and is easily America’s longest-serving political prisoner.

Peltier was a leader of the American Indian Movement, or AIM, a grassroots group of activists focused on drawing attention to federal treaty rights violations, discrimination and police brutality targeting Native Americans.

The FBI and U.S. attorney’s office scrambled to put him in prison when they couldn’t figure out who killed two FBI agents during a 1975 shootout on Pine Ridge Reservation in South Dakota. They never had evidence that he killed anyone, and his trial was outrageous: Prosecutors hid exculpatory evidence. The FBI threatened witnesses into lying. Peltier was separated from his co-defendants, all of whom were acquitted on the grounds of self-defense. A juror admitted she was racist against Native Americans on the second day of the trial but was allowed to stay on.

The U.S. government has since has acknowledged its egregious misconduct in the trial, with one federal judge concluding in 2003 that the government’s behavior in the case “is to be condemned.”

Nonetheless, Peltier was convicted of aiding and abetting whoever did kill the FBI agents on the grounds of simply being present that day, and sentenced to prison for two consecutive life terms. The prosecutors subsequently admitted they have no idea who shot the agents at point-blank range.

Peltier, who is now 79 years old, has maintained his innocence this entire time, which is certainly a factor in why he hasn’t been paroled. His decadeslong parole process has been so problematic that United Nations legal experts last year made the unusual decision to revisit his case. Last summer, they called on Biden to release him immediately.

Peltier is currently deteriorating in a Florida maximum security prison, where he’s almost always confined to a cell with inches of space to move within and in a near-constant state of lockdown. He uses a walker to get around. He is blind in one eye from a partial stroke. He has severe health concerns related to diabetes and an aortic aneurysm. It’s bad.

The FBI continues to oppose his release, though, so that’s why he’s still there. The bureau’s stated reason for why he should stay in prison, forever, is utter nonsense.

Biden could release Peltier at any time, unilaterally. It would mean going against the FBI’s wishes. That’s where the rub is. In the meantime, the president is facing increasing pressure from within his own party to let Peltier go home.

Beyond the repeated appeals from members of Congress, the Democratic National Committee last year unanimously passed a resolution calling on Biden to grant clemency to Peltier. Last month, hundreds of activists and Indigenous leaders held a rally outside the White House demanding Peltier’s freedom. Amnesty International, the prominent human rights organization usually focused on freeing political prisoners in other countries, recently launched a new campaign aimed squarely at urging Biden to release Peltier.

Two prominent Indigenous leaders recently signaled that tribal leaders and Native rights advocates plan to make Peltier’s freedom a priority issue in the 2024 presidential election.

“It’s simply a choice we fully expect him to make,” Fawn Sharp, president of the National Congress of American Indians, said of Biden releasing Peltier.

“Being silent on this issue, given all the facts, given all the advocacy, given all the issues raised by Indian Country ― when it is your choice and you’re the top person and you choose to ignore it, you’ve become complicit in this injustice for Indian Country,” she said.

A White House spokesman did not respond to a request for comment.