Maryland Gov. Martin O'Malley speaks at a rally in support of repealing the state's death penalty in January. (AP Photo/Patrick Semansky)

The Maryland legislature voted Friday to abolish the death penalty, which would make the state the sixth in as many years to end capital punishment and add to a canon of liberal policies recently embraced by state leaders.

The 82 to 56 vote in the House of Delegates, which followed two hours of debate, reflected a growing unease among lawmakers in Maryland and across the country that the risk of putting an innocent person to death remains too great with the death penalty in place.

The legislation, which passed the Senate last week, now goes to the desk of Gov. Martin O’Malley (D), who claimed a long-sought victory. Aides said he will sign the bill in coming weeks.

Since taking office in 2007, O’Malley has urged lawmakers to end capital punishment. He has also led successful efforts to legalize same-sex marriage, extend in-state college tuition rates to illegal immigrants and raise income taxes on wealthy residents.

In an interview, O’Malley credited the grass-roots lobbying efforts of the NAACP and faith leaders, turnover in the state Senate and some last-minute conversions with helping achieve an objective that had previously eluded him.

“I’ve felt compelled to do everything I could to change our law, repeal the death penalty, so that we could focus on doing the things that actually work to reduce violent crime,” said O’Malley, who rose to political prominence as a tough-on-crime mayor of Baltimore.

Repeal advocates said the win in Maryland — which has five prisoners on death row but hasn’t executed anyone since 2005 — would continue momentum nationally.

Benjamin T. Jealous, president of the NAACP, which has made repeal of the death penalty a national priority, noted that Maryland would become the first state south of the Mason-Dixon line to do away with capital punishment.

“This is a big day for Maryland. It’s a bigger day for the country,” said Jealous, who watched Friday’s vote in Annapolis from the House gallery and appeared at a news conference with O’Malley afterward. “It shows that the anti-death penalty movement is accelerating.”

He said that repeal advocates are within striking distance in Delaware, Colorado, New Hampshire and Kansas.

Although the death penalty remains on the books in 33 states, many are using it more sparingly than in the past. Last year, 77 people were sentenced to death nationally, the second-lowest number since capital punishment was reinstated in 1976, according to the Death Penalty Information Center.

“State after state is deciding that the death penalty is simply not worth the risks and costs to retain,” Richard Dieter, the executive director of the center, said Friday, predicting that Maryland “won’t be the last” to end capital punishment.

During Friday’s debate in the House, opponents of the repeal bill argued that capital punishment can be an important law-enforcement tool and should be kept on the books for heinous cases, several of which were recounted in graphic detail.

“I wish that we did not need the death penalty . . . but I’ve seen the worst of the worst, and I know it’s necessary,” Del. C.T. Wilson (D-Charles), a former prosecutor, told colleagues.

But his side was outnumbered by delegates who said they’ve come to view life without the possibility of parole as an acceptable alternative.

More than a dozen members made references to Kirk Bloodsworth, a former death-row inmate who was exonerated by DNA evidence and released from prison in 1993. Bloodsworth, a former Marine convicted of raping and murdering a 9-year-old girl in Baltimore County in 1984, watched the proceedings Friday from the House gallery.

“Human beings cannot devise a system of justice that is perfect,” said Del. Anne Healey (D-Prince George’s). “What I can’t live with is, if we make a mistake, it costs somebody else his life.”

A couple of members said they had reached their decision only in recent days.

“I’m a reluctant convert to supporting repeal, but a convert nonetheless,” said William J. Frank (R-Baltimore County), citing a “respect for human life.”

Maryland voters could still get the final say on the measure. A provision in the state constitution allows citizens to petition recently passed laws to the ballot, as happened with same-sex marriage legislation last year.

Senate President Thomas V. Mike Miller Jr. (D-Calvert) has said the death penalty is likely to be placed on the 2014 ballot, although no group has announced plans to spearhead an organized effort to collect signatures.

The outcome of a ballot measure would be far from certain. A Washington Post poll released last month showed that a majority of Marylanders want to keep the death penalty despite widespread skepticism as to whether it is a deterrent to murder or is applied fairly.

Repealing the death penalty was not an issue that O’Malley campaigned on in 2006 when he first defeated then-Gov. Robert L. Ehrlich Jr. (R). But in December 2006, a month before he took office, the Court of Appeals ruled that the state’s procedures had not been properly adopted and halted executions until new regulations could be issued by the administration.

It was then that O’Malley, a practicing Catholic, said he sensed an opening to pursue a long-held belief of his.

Rather than put forward new regulations that would allow the death penalty to resume, O’Malley focused on lobbying the legislature for repeal.

In high-profile testimony shortly after he took office in 2007, the governor argued that capital punishment is “inherently unjust,” does not serve as a deterrent to murder and consumes resources that could be better used to prevent crime.

In 2009, after two repeal bills sponsored by lawmakers had failed, O’Malley decided to put the full weight of his office behind the measure and sponsor it himself, even though it was unclear if there were enough votes in the Senate.

That measure was rejected by the chamber, with members choosing instead to tighten evidentiary standards in capital cases.

Since then, several lawmakers have suggested that their attempt to “fix” the death penalty in 2009 was insufficient.

Those include Sen. Robert A. Zirkin (D-Baltimore County), the primary author of the 2009 amendment, which limited capital cases to those with DNA evidence, videotaped confessions or videotape of the crime itself.

Zirkin said he wrestled with his position for months and still was conflicted as he cast his vote for the repeal, expressing no moral qualms about putting to death people who are guilty beyond a shadow of a doubt.

“From an emotional standpoint, I want to kill these people myself,” he said. “But that’s a different question than whether, legally, the state should be involved in their death.”

In the weeks before the vote, three other members announced that they would vote for the bill, citing a variety of reasons, including visits from families of murder victims who opposed capital punishment.

“The idea of strapping someone down and deliberately taking their life — it was a little difficult for me,” said Sen. John C. Astle (D-Anne Arundel). “I didn’t come to my decision easily.”

The outcome in the House on Friday was expected, but that didn’t lessen the drama. House Speaker Michael E. Busch (D-Anne Arundel) characterized his chamber’s death-penalty vote and its legalization of same-sex marriage last year as two of the most emotional and important undertaken by state lawmakers.

Aaron C. Davis contributed to this report.