Castón, who did not respond to requests for comment, was released from prison last year, nearly three decades after he killed an 18-year-old man in a 1994 parking lot shooting. In 2021, while still a prisoner, he was elected to the D.C. Advisory Neighborhood Commission, becoming the first incarcerated person voted into public office in the city.

Council Chairman Phil Mendelson (D), who nominated Castón to the 12-member sentencing commission, said in an interview that the panel expressed interest in having a previously incarcerated person join the group. Linden Fry, the commission’s executive director, said members began discussing the addition of a person who had been incarcerated after they learned “how other sentencing commissions in the United States have added returned citizen members.”

“A formerly incarcerated, justice-involved individual can offer a relevant and unique point of view unavailable to other members,” Fry said.

But Matthew M. Graves, the U.S. attorney for the District, whose office prosecutes felony cases in the city, questioned Castón’s integrity in a letter to Mendelson. Graves said the nominee would likely advocate for lesser sentencing ranges that would make it even harder for prosecutors to secure prison time for people convicted of firearms violations in the nation’s capital.

At a council hearing in December, Castón said, “If confirmed, I would be a fierce advocate for sentences that balance accountability, public well-being and human dignity.”

The debate over Castón is yet another instance of discord among top local officials about how to ensure public safety and make the criminal justice system more efficient in the District, which has been enduring spikes in violence, including homicides. More people were slain in D.C. in 2023 than in any year since 1997. The Bowser administration, Graves’s office and some judges repeatedly and publicly pointed fingers of blame at one another last year over aspects of the city’s crime crisis.

Minimum and maximum sentences for crimes are established by District law, and D.C. Superior Court judges impose prison time within those ranges. In deciding what a particular sentences should be, judges rely on a manual containing elaborate formulas for calculating an appropriate prison term based partly on a defendant’s criminal background and the specifics of the offense.

The resulting guidelines are advisory, and judges can depart from them — although data published by the commission last year showed that judges’ sentences hewed to the recommendations in nearly 97 percent of felony cases. The sentencing commission governs the manual and any revisions to it.

Castón would be the D.C. Council’s voting representative on the commission. But whether a man with a murder conviction should be part of that process has prompted debate among top D.C. officials, revealing the depths of ideological fissures among some of them. Council member Brooke Pinto (D-Ward 2), chairwoman of the council’s public safety committee, said she would not support Castón’s nomination, suggesting he lacks expertise in “the nuanced landscape of our D.C. sentencing guidelines.”

After Graves outlined his reservations in a letter, Mendelson responded by expressing support for Castón and accusing Graves of blaming the sentencing commission for problems created by the U.S. attorney’s office.

In the days leading up to Tuesday’s vote, Graves and Mendelson sparred in letters over the merits of Castón’s nomination. Gregg Pemberton, the chairman of the police union, also opposed the nomination, while a D.C. police spokesman said the department would work with all members of the commission.

Nazgol Ghandnoosh, a voting member of the commission who was appointed by the Superior Court chief judge, said Castón would add key insight to the group.

“Trying to identify problems with this nomination is completely misguided in terms of having meaningful conversations about what to do about crime,” she said. Ghandnoosh is the co-director of research at the Sentencing Project, a group that advocates to “minimize imprisonment.”

Asked about Castón’s vision for criminal justice and sentencing, Mendelson acknowledged that he did not probe Castón’s positions, saying he was primarily focused on his background as a formerly incarcerated person.

Castón, who has advocated for restorative justice and prison reform, has also done consulting and work with criminal justice organizations such as the Justice Policy Institute, which advocates against mass incarceration and seeks to reduce disparities in the justice system. But Mendelson disagreed that Castón’s appointment as the council’s voice on the commission would be a statement on the direction the council hoped to take criminal justice reform in the city.

“It’s not a policy position but a perspective,” Mendelson said.

Graves, in a Jan. 2 letter to Mendelson, raised questions about Castón’s past. He pointed to a 2021 decision by a Superior Court judge to deny his petition for early release under a D.C. law meant to give fresh chances to people who have been imprisoned for many years. The judge wrote that the court was “highly troubled by a specific characteristic that has been displayed consistently throughout his post-conviction history that seems at odds with any claim to integrity.”

Castón claimed innocence before he accepted responsibility for the murder. Mendelson, in a memo to the Council on Monday, acknowledged that Castón “pursued an innocence claim which was denied repeatedly because it was false.” But Mendelson highlighted a judge’s finding that Castón also made “enormous strides” while incarcerated.

In his letter, Graves blamed the commission for inadequate sentencing outcomes in the District. In 2022, according to Graves, 57 percent of people sentenced on his office’s most commonly charged firearms offense — carrying a pistol without a license — were sentenced to probation. An additional 30 percent received relatively short jail terms.

“These outcomes are a feature, not a bug, of the District’s Guidelines,” Graves said in the letter.

At a Dec. 5 breakfast with the council, Graves expounded on his problems with the existing sentencing guidelines and called for a “wholesale” review of the manual. In that meeting, he specifically criticized a 2018 change by the commission, when members eased sentencing guidelines for people with prior felony convictions who are found guilty of illegal gun possession.

“The fact that this is so defense-friendly really isn’t surprising if you look at the composition on [the commission],” Graves said at the breakfast. “There are voting members on that commission who are explicitly associated with organizations that are in the decarceral movement. … If people are fine with that, that’s fine to have these guidelines. But if they want to change, then you have to look at who are the voting members on the commission?”

Mendelson said it is misleading for Graves to blame guidelines that have been around for two decades.

“Focusing on the sentencing commission is turning the spotlight somewhere else,” Mendelson said, pointing to Graves’s prosecution rate. The U.S. attorney’s office declined to prosecute 56 percent of cases in D.C. in fiscal year 2023, which ended Sept. 30. Graves has pointed to problems with the city’s crime lab, which went two years without certification in some departments, and court decisions that restrict police actions and make prosecutions in gun cases difficult.

The debate over Castón’s nomination comes as every corner of D.C.’s criminal justice system is under public scrutiny. In respond to rising crime, officials began turning away from progressive strategies enacted in recent years. Instead, Mayor Muriel E. Bowser (D), new Police Chief Pamela A. Smith and some lawmakers have cited the need for greater accountability, advocating for tougher sentences for adults and juveniles who commit violent crimes.