The 27-20 vote sent the bill to the House of Delegates, where repeal supporters believe they have enough backing to send the legislation to the governor.
Two Republicans — Sens. Edward R. Reilly of Anne Arundel County and Allan H. Kittleman of Howard County — joined 25 Democrats in supporting repeal. Ten Democrats and 10 Republicans opposed the legislation.
The Senate has been viewed by repeal proponents as a tougher challenge than the House. In 2009, the last year O'Malley pushed to end capital punishment, the effort ended in a compromise that narrowed the circumstances under which the death penalty could be sought.
This year, the NAACP decided to make repeal in Maryland a priority and urged O'Malley to include it in his legislative agenda. Senate President Thomas V. Mike Miller, despite his personal support for capital punishment, promised to allow an up-or-down vote in his chamber if O'Malley could show he had the votes to pass the bill.
After the vote, Miller gave O'Malley — along with the NAACP, the Catholic Church and other religious groups — credit for the bill's passage.
"He chose to push it hard. I think he'll meet with success in the House of Delegates," said Miller, a Calvert County Democrat. But he also predicted a close vote if the bill is petitioned to a referendum in 2014, as he expects it to be.
Miller said death penalty opponents are right when they say the system is "broken," but said it should be corrected instead of abolished. "Justice should be sure and justice should be swift," he said.
A breakthrough for death penalty opponents came when Sen. Robert A. Zirkin, a Baltimore County Democrat, reversed his previous opposition to repeal and provided the sixth vote needed to approve the bill in the Judicial Proceedings Committee and send it to the Senate floor. There, opponents of the legislation tried repeatedly but failed to win approval of amendments creating various exceptions to full repeal.
Zirkin took to the floor Wednesday to say he had no sympathy for killers such as the five men currently on death row in Maryland for murders committed as far back as 1983.
"There are horrible monsters," Zirkin said. "If you were always 100 percent sure, I think we would all agree they don't deserve to live."
But Zirkin said he couldn't accept even the remote possibility that Maryland could execute somebody who was innocent.
That was the argument that ultimately swayed Kittleman, who said he was still wrestling with the decision as floor debate got under way last week.
"DNA evidence isn't always conclusive, and we've made that the Holy Grail," Kittleman said. He said he was swayed to believe that DNA evidence "indicates presence, not guilt."
"I don't think I'm protecting the criminals. I think I'm protecting the innocent," Kittleman said.
As if to underscore that point, Kirk Bloodsworth — exonerated by DNA testing after being sentenced to death in Baltimore County for the murder of a young girl — was in the Senate gallery Wednesday to witness the vote.
Supporters of capital punishment countered that since 2009, Maryland has had one of the most restrictive death penalty laws in the country. Prosecutors are able to seek the death penalty only when they have biological evidence, a videotape of the crime or a video-recorded confession by the killer.
Senate Minority Leader E. J. Pipkin, an Eastern Shore Republican, said a case such as Bloodsworth's couldn't happen today. Pipkin said he was tired of hearing repeal supporters' constant repetition of his name. Sen. Jamie Raskin, the floor leader for the pro-repeal forces, said that while some senators may be suffering from "Kirk Bloodsworth fatigue," he was not.
After the vote Bloodsworth said he was "tickled pink" at the outcome, adding that an unjust conviction is something that "can happen to anybody."
The burly ex-waterman caught Sen. Brian E. Frosh, a death penalty foe who chairs the Judicial Proceedings Committee, in a congratulatory bear hug.
Frosh, a Montgomery County Democrat, said he was relieved by the Senate vote.
"Nobody listens to the stories of the folks who committed these horrible crimes without some wish for vengeance, but this is the right thing to do," he said.
The bill does not directly affect the inmates currently on death row, but it expresses the Senate's view that if the governor commutes their sentences, it should be to life without parole. Raskin said that under the state Constitution, the legislature could not put any statutory limit on the governor's commutation and pardon powers.
The last time Maryland executed a convicted murderer was in 2005, when Wesley Baker, 47, received a lethal injection for the 1991 killing of 49-year-old Jane Tyson in the parking lot of Westview Mall.
Like four of the five men on Maryland's death row, Baker was an African-American whose victim was white. A 2003 study by University of Maryland researcher Raymond Paternoster found that killers of white victims were two to three times more likely to be sentenced to death than those who murdered blacks. He also found wide discrepancies from jurisdiction to jurisdiction, with killers who committed their crimes in Baltimore County far more likely to receive the death penalty than those in Baltimore city.
Disparity in sentencing was one of the chief arguments raised by supporters of repeal, along with the cost of administering the system and the possibility of error.
Critics of the governor's bill argued that execution should remain an option for punishing the "worst of the worst," including inmates who commit murder in prison and killers who murder in the course of a rape.
"We are talking about crimes against humanity," said Sen. Christopher Shank, a Washington County Republican.
Sen. Nancy Jacobs recounted the details of a particularly gruesome murder from Maryland's recent past — the 1987 torture, sexual assault and murder of Dawn Garvin by Steven Oken in Baltimore County. Jacobs, a Harford County Republican, said the victim's family believes in the biblical injunction that those who kill deserve to be executed, as Oken was in 2004.
"It's for Dawn Marie Garvin's family," she said in explaining her no vote.
Shari Silberstein, executive director of the anti-execution group Equal Justice USA, said final enactment of repeal would make Maryland the sixth state in the past six years to abolish capital punishment. She said her hope is that Maryland's likely action increases the momentum behind repeal efforts nationwide.
"There are several states teed up. Delaware and Colorado are looking possible this year or next," she said.
Silberstein said what's happening in Maryland and the role of O'Malley are symbolic of a broader cultural shift in attitudes toward the death penalty. She said both executions and death sentences have been on the decline nationally and that opposition to capital punishment is no longer politically dangerous.
"Five or 10 years ago, a governor who wanted to be president would not have made the death penalty such a banner issue," she said.