Prosecutors and police rarely get detailed descriptions of murders from self-confessed killers, but that’s what Nathaniel D. Simms gave them.

Days after Simms was arrested in the aftermath of a March 2010 drive-by shooting that capped one of the District’s deadliest outbreaks of violence in decades, he agreed not only to tell how he fired an AK-47-style assault rifle into a crowd of mourners but also to identify the other men who participated in three shootings over eight days that left five dead and eight injured.

Late Tuesday, D.C. prosecutors paid Simms a kind of tribute. In a court filing, they called him the “single most important witness” in the case against the five other men convicted in the attacks and recommended that he receive a 25-year prison sentence. Simms pleaded guilty to five counts of second-degree murder and two counts of conspiracy for his role in the shootings.

Simms 28, of Capitol Heights is scheduled to be sentenced Oct. 19. According to District sentencing guidelines, he faces a minimum of five years in prison and a maximum of 40 for each murder. In their memo, prosecutors Michael Brittin, Bruce Hegyi and Adam Schwartz recommended 60 years for Simms, with all but 25 suspended, and five years of probation.

D.C. Superior Court Judge Michael L. Rankin is not required to adopt the recommendation, and he could sentence Simms to a longer term.

The recommendation outraged some family members of the people killed in the shootings.

“It’s so sad to know you can kill someone — no, aim an AK-47 at innocent people and then cooperate and you are rewarded with a light sentence,” said Nardyne Jefferies, mother of Brishell Jones, 16, the youngest victim of the shootings.

Others seemed resigned. “I don’t think 25 years is enough,” said Lavenia Attaway, whose sons Jamal, 23, and Kevin, 31, were injured in the drive-by, but she praised Simms for helping authorities. “But I understand.”

Simms gave a detailed account to authorities and identified the other men by name: Jeffrey Best and Robert Bost, both 23; Orlando Carter, 22; Carter’s brother Sanquan, 21; and Lamar Williams, 24.

Sanquan Carter had been arrested days before the March 30 drive-by shooting on South Capitol Street. After that attack, authorities had Simms and Orlando Carter in custody. Two weeks after his arrest, Simms agreed to cooperate, identifying Best, Bost and Williams.

Simms gave a detailed account of his friends’ roles, motives and plan.

He told police that they had mistakenly arrested a 14-year-old in the aftermath of the drive-by shooting, saying the teen was not involved.

During a two-month trial this past spring, Simms testified that he pointed the assault rifle out of the passenger window of a rented minivan driven by Orlando Carter and, with Best and Bost, shot into a crowd of mourners who had attended the funeral of Jordan Howe earlier on March 30.

Howe, 20, was fatally wounded in the first of the three shootings when, on March 22, Simms, Best and the Carter brothers fired on a group outside a party because Sanquan Carter mistakenly believed that Howe had stolen his mock-gold bracelet.

Over five days of testimony, often through sobs and tears, Simms detailed the shootings to a packed courtroom. Judges and courthouse employees swelled the ranks of observers in the courtroom as Simms described the shootings.

Last month, Best, Bost and Orlando Carter were sentenced to life in prison without parole after being convicted of multiple counts of first-degree murder and other charges associated with the shootings. Sanquan Carter was sentenced to 54 years in prison, and Williams — who was not present at the shootings but helped the others arm themselves and plan the attacks — was given 30 years behind bars.

Simms has been in protective custody since he agreed to cooperate with authorities. In their sentencing memo, prosecutors said their recommendation was an attempt to strike an “appropriate balance between punishing Simms for his crimes while crediting him for his most meaningful contribution to the successful detection and prosecution of other offenders.”

Defense attorneys for the five other men said the recommendation was an attempt to send a message to others who might cooperate with authorities. “They want to make [Simms] the poster child of cooperating witnesses,” said Todd S. Baldwin, Bost’s attorney.

Michael O’Keefe, Best’s attorney, expressed concern that the sentence might induce other suspects to fabricate details in hopes of getting lighter sentences.

“You never know if what cooperators are going to say is the truth because they are trying to save their own skin,” he said.

In their 3o-page memo, prosecutors hailed Simms as key to their case — a different assessment from the one they offered during the trial, during which defense attorneys attacked his story and his motives.

At that time, prosecutors insisted that Simms was only part of a case that also included DNA evidence, cellphone records and testimony from several other witnesses, although they were able to obtain that evidence in part because of Simms’s cooperation.