Federal prosecutors in the District late Friday asked a judge to nullify the life sentence of 1980s drug kingpin Rayful Edmond III and instead resentence him to 40 years in prison.

Edmond, arrested in 1989, has been incarcerated for three decades. It was not immediately clear how much more time he would have to serve on the D.C. sentence if the petition is granted by a judge. Lawyers said that could depend on how sentencing rules, including those regarding “good time” credit, might affect his case.

In February, the U.S. Attorney’s Office for the District of Columbia filed a motion requesting that Edmond’s life sentence be reduced, but prosecutors didn’t initially offer a specific recommendation.

Edmond had cooperated with authorities over nearly two decades, helping them understand the workings of the drug trade and convict about 100 other dealers, prosecutors said. In addition, they said, Edmond helped in the investigations of numerous cold-case slayings, offering details about friendships, rivalries or feuds among victims and suspects.

The final say on whether Edmond gets a break will rest with U.S. District Judge Emmet G. ­Sullivan.

Edmond’s attorney, Jason Downs, declined to comment Friday on the filing. But in previous court filings, Downs repeatedly told the judge he believed Edmond should be given time served in exchange for his cooperation.

A hearing is scheduled in October before Sullivan where witnesses on behalf of Edmond are expected to testify. Sullivan also ordered Edmond to be present. Edmond, who is in witness protection as a result of his cooperation, appeared at a hearing earlier via television monitor from an undisclosed prison.

Edmond, 54, oversaw an operation that brought up to 1,700 pounds of cocaine a month into the District in the mid-1980s. At one point, law enforcement officials estimated he was raking in as much as $2 million a week.

The crack cocaine epidemic also contributed to the city’s rising homicide rate at the time, pushing Washington to be nicknamed the “nation’s murder capital.” Authorities said Edmond’s enforcers were linked to as many as 30 slayings, although Edmond was never convicted in any homicides.

Following his arrest in 1989 and a jury trial in federal court, Edmond was sentenced to life without parole for drug distribution in the District.

The resentencing request comes as federal prosecutors in the District have objected to a move by city lawmakers to expand a law that allows people who committed serious crimes as juveniles to seek early release after serving 15 years in prison. An amendment before the D.C. Council would increase the pool of eligible applicants to those who were as old as 24 when they offended.

Jessie K. Liu, the U.S. attorney for the District, has noted that Edmond has served more than 30 years and that he was not convicted of a violent crime.

The judge’s decision in the D.C. case will not directly affect the 30-year sentence Edmond has yet to serve for a separate conviction in Pennsylvania for dealing drugs from a prison there. Prosecutors in Pennsylvania have not indicated whether they also plan to request a reduction. Edmond has not yet begun serving that sentence because it runs consecutive to his life sentence.

Last week, the District’s attorney general’s office released a survey in which about 500 D.C. residents were nearly evenly split on whether they believed Edmond should have his sentenced reduced or remain in prison for life.