Dwuan Dent and Antwan Askia were on opposite sides of an East Baltimore drug turf war in the 1990s that killed at least four people, according to federal prosecutors who charged Dent with murder and conspiracy and Askia with various drug counts.

Both were convicted only of drug distribution charges, but because of tough-on-crime guidelines that imposed greater penalties for crack than powder cocaine, Dent was sentenced to more than 17 years in prison and Askia to 20.

Now Dent and Askia are among scores of prisoners across the country who are being released early — the beneficiaries of efforts to change those sentencing guidelines that critics say disproportionately affected low-income people and minorities who faced longer prison terms for crack-cocaine charges. Some authorities, however, warn that potentially dangerous criminals with records of violence also could be released.

Since the 1980s, possession of one gram of crack carried the same penalty as 100 grams of powder cocaine. The bipartisan U.S. Sentencing Commission voted unanimously last year to narrow the gap between the guidelines that applied to each drug, and the change is being applied retroactively.

An estimated 12,000 prisoners across the country are eligible for release as the lighter sentencing guidelines are applied to their cases. Federal prosecutors and public defenders in Maryland are reviewing some 900 cases, so far recommending the release of 24 inmates; federal judges have signed off on those releases. Officials say another two dozen are likely to be released before the end of the year, and a few more after that.

While only those convicted of drug offenses — and no other charges — are eligible for review, Maryland U.S. Attorney Rod Rosenstein said prosecutors in some cases didn't pursue convictions on harder-to-prove allegations of violence because the drug charges carried such heavy sentences. He declined to comment on specific cases.

"In some cases, their record may not reflect the violent crimes in which they were engaged," Rosenstein said. "When prosecutors had these crack penalties, they used those to incarcerate people for lengthy periods of time without proving the violence. It's much more complicated to prove that somebody's involved in shootings and murder."

But Sapna Mirchandani, a federal public defender in Maryland who is leading an effort to identify inmates who should be released, took exception to that assessment.

"The fact that they were able to use the amount of crack in their possession to trump up the sentence shows how the crack law was being used to imprison people for large chunks of time with little in the way of investigation and proof," she said.

Widely believed to be prompted by the overdose death of University of Maryland basketball star Len Bias, the law was changed in the mid-1980s to establish the 100-to-1 ratio in sentencing guidelines between crack and powder cocaine. That ratio has now been reduced to 18-to-1. Advocates for the change, including U.S. Attorney General Eric Holder and various civil liberties organizations, say it is long overdue.

Crack is more prevalent in poor communities, and the law's opponents contend it has disproportionately affected African-Americans: 85 percent of offenders sentenced under the law have been African-American, and 5 percent white.

Marc Mauer, executive director of the Sentencing Project, an organization advocating criminal justice reform, said the crack offenders selected for release were treated unfairly under the old sentencing law and deserve a second chance.

"In most of these cases, they've been locked up for 10 years or more," he said. "Ten years is a very long time, and they're not the same people they were 10 years ago."

Facebook didn't exist when Askia was sent to federal prison for crack possession after being convicted along with members of a Baltimore gang linked to several deaths, including that of Northern High School's star quarterback, Rocco Colavito Cash, who prosecutors said was mistaken for a rival gang member. Askia was never implicated in the killing, and he argued in an appeal that he was unfairly tried together with the drug co-conspirators who were charged in the death.

On Nov. 6, after serving 10 years of a 20-year sentence, Askia logged on to the social networking site and updated his current location: Baltimore.

He added "Baltimore Ravens" to his favorite teams, and "liked" the music of Lauryn Hill. He picked his favorite movies: "Set it Off," "The Usual Suspects," and "Friday" — all of which came out in the late 1990s, before he was incarcerated.

Askia, now 37, declined to be interviewed. According to court documents, he says he worked in prison to better himself. In a petition to the judge in his case, he said he completed a 15-credit course in business management from Kent State University, as well as real estate courses and an apprenticeship in data entry.

"Throughout the course of his incarceration, petitioner has not only grew in age, but he's grown in maturity and decision making," Askia personally wrote in a legal brief he filed in the case.

Dent, who is 38, also attached paperwork in a separate court filing showing that he had earned a GED and taken college-level accounting, business law and English classes. Of his 12 co-defendants who were convicted, at least eight others have applied for reductions under previous crack-sentencing adjustments, though only four were successful, according to court records.