Maryland Gov. Martin O’Malley (D) on Wednesday will take a key legal step toward commuting the prison terms of inmates serving life sentences for murder — a first for the governor, who won the state’s top office on a reputation as a tough-on-crime, big-city mayor.

O’Malley will file notice that he is considering freeing a Prince George’s County woman who was convicted 27 years ago of setting up a man for a robbery in which he ended up being shot and killed by the woman’s boyfriend.

O’Malley is also poised to commute the sentence of a Baltimore man whose conviction for a shooting in the mid-1980s has gained national attention since the only independent witness in the case recanted his testimony.

Commutations are risky decisions for governors, and they have gained heightened scrutiny since 2009, when an ex-convict killed four police officers nine years after Arkansas Gov. Mike Huckabee (R) commuted his sentence. This year, on his final day in office, Mississippi Gov. Haley Barbour (R) pardoned nearly 200 people, setting off a political and legal firestorm.

Aides to O’Malley said that after denying 57 requests to commute sentences in the past six years, the cases that he will make public on Wednesday could meet an end for different reasons.

In the Prince George’s case, a wide discrepancy exists in punishments for the woman and her co-defendant. She has been incarcerated far longer than the co-defendant, who pulled the trigger. In the Baltimore case, no clear answers exist about culpability. Aides said another important consideration for O’Malley has been that both inmates have given every indication that they could return to society successfully.

Rick Abbruzzese, O’Malley’s director of public affairs, said that reaching this final, public stage of the process was “significant” for the governor, who now wants to make sure that anyone who might object has a chance to be heard. Most notably, aides said, they are hoping the public notice reaches relatives of the Prince George’s victim, whom members of O’Malley’s administration have not been able to find.

If no objections are raised, probably in a matter of weeks, O’Malley’s decision will send the cases back to the state’s parole commission, which has already issued recommendations for release, although the proposed timings of those releases have been shared only with the governor’s office.

If O’Malley does decide to free one or both, it would mark a major break with one of the clearest policies that he and other recent Democratic governors in the state have maintained.

O’Malley, former governor Parris N. Glendening and other recent Democrats have maintained near bans on commuting sentences of inmates convicted of murder. Former governor Robert L. Ehrlich Jr. (R) had commuted and pardoned hundreds during his term, although only a small fraction of them had been convicted of murder.

O’Malley has also been stingy with pardons of former convicts who have gone on to live cleanly for many years after prison.

In the Prince George’s case, aides said the evidence that O’Malley seems to have found most convincing was a profound discrepancy between the prison term served by the man who pulled trigger and the woman who initiated the crime.

In November 1984, Tamara Settles, then 26, met a Southeast Washington man in the Silver Star Night Club on E Street NW.

Settles “struck up a friendship” with Charles Fowler, then 53 and a D.C. resident. She later left the bar with him, according to the original police report.

Settles lured Fowler to a street in Hyattsville where her boyfriend was waiting. That man, Herman Ray Rockingham III, “opened the driver’s door and with gun in hand fired two shots at the victim and at the same time demanded the victim’s wallet,” the police report said.

One of the shots struck Fowler in the head, and he died five days later in Prince George’s Hospital.

Rockingham, the shooter, pleaded guilty and was sentenced to 15 years to life. He later was able to get that reduced and was released after about nine years.

Settles chose to go to trial and was convicted of felony murder and sentenced to life without parole.

Now 53, Settles has served three times the number of years as Rockingham. From behind bars, she has completed 12 years of drug addiction therapy, earned an associate’s degree, worked as a volunteer mentor and is taking classes toward a bachelor’s degree from Morgan State University.

To get this close to release, nonetheless, has been no easy decision for O’Malley, said Kristen Mahoney, the governor’s top adviser on crime, who recounted a painstakingly detailed review of the cases undertaken by O’Malley in a conference room in the State House.

“I can’t underscore how serious he takes this responsibility, especially given his role in Baltimore,” Mahoney said Tuesday. “He has seen these victims, and while he doesn’t know these particular shooters, he knows these shooters’ stories.”

O’Malley’s announcement, which to comply with state law will be filed Wednesday in a legal newspaper, comes just weeks before a new deadline for him to decide any parole requests that have been lingering for 180 days.

Republicans and Democrats in the state legislature have in recent years criticized O’Malley for not acting in a timely fashion on parole decisions. Last spring, the General Assembly passed a bill requiring the parole board’s recommendations for those who have served at least 25 years to take effect after 180 days if O’Malley has not disapproved of them in writing.

O’Malley’s aides said most of the requests that the governor gets from the state’s parole commission are for commutations, not parole. The governor and his staff have quietly investigated and issued denials since he took office in 2007. O’Malley was not required to issue decisions on commutations by the coming deadline, but aides said he wanted to comply with the spirit of the law passed by the legislature.

Unlike in Baltimore, where as mayor he would show up at crime scenes, O’Malley has drawn little attention for his crime-fighting efforts since becoming governor.

He pushed the state to clear its backlog of untested DNA samples early in his first term, and promoted tougher sex-offender legislation after the killing of an Eastern Shore girl. But he has often used executive powers to quietly change the way the state targets its most violent offenders for incarceration

The second inmate who could be freed is Mark Farley Grant. He was 14 when he allegedly shot another teenager and stole his coat in a Baltimore street robbery in 1983.

The case has been major cause of the Innocence Project, a student-faculty law clinic at the University of Maryland. Since the clinic took on Grant’s case, a friend of the victim recanted his account of the altercation and fingered Grant’s co-defendant in the case as the shooter.

Researcher Madonna Lebling contributed to this report.