Maryland has become the eighteenth US state to abolish the death penalty, replacing it with life in prison without parole.

The measure was signed in to law on Thursday by the state's Democratic Governor Martin O'Malley, an outspoken critic of capital punishment.

"Evidence shows that the death penalty is not a deterrent, it cannot be administered without racial bias and it costs three times as much as life in prison without parole," O'Malley said in a statement.

It would be too much of a travesty if we executed an innocent person. Allan Kittelman, Maryland State Senator

Kirk Bloodsworth, one-time Maryland death row inmate, attended the crowded ceremony which repealed the law that could have killed him.

Al Jazeera's Kristen Saloomey met Bloodsworth, who wrongfully served nine years for the rape and murder of a nine-year-old girl in 1984.

He was the first person in the US to be freed because of DNA evidence after being convicted in a death-penalty case.

After regaining his freedom, Bloodsworth campaigned for the end of the death penalty.

"If it can happen to me it can happen to anyone. I tell them my story, I was a marine with no record," he said.

"I was happy, I killed the thing that almost killed me."

Bloodsworth's case shone a spotlight on the death penalty and what his fate could have been was instrumental in pushing the repeal through.

"It would be too much of a travesty if we executed an innocent person I just couldn’t let that happen, Kirk helped me to understand that," Senator Allan Kittelman told our correspondent.

The bill will not apply to the five men the state has on death row, but the governor can commute their sentences to life without parole.

O'Malley has said he will consider them on a case-by-case basis.