AUGUSTA – A bill to shorten sentences for some offenses while revamping probation rules to create needed space in Maine’s crowded prison system was signed into law Wednesday by Gov. John Baldacci.

The new law also gives state corrections officials authority to place some inmates with two years remaining on their sentences in supervised community confinement, provided it does not overtax the probation system.

Among numerous other changes, the bill increases time off for good behavior to nine days per month from five days. The “good time” provision would not apply to those serving time for murder, sex crimes or domestic violence.

The lengthy and heavily debated bill, LD 1903, is an outgrowth of a special commission’s study of prison overcrowding and Maine’s sex-offender laws. Under separate legislation signed a day earlier by Baldacci, the prison study will continue.

“We still have more work ahead,” said Rep. Patricia Blanchette, House chair of the Criminal Justice and Public Safety Committee, which refined the bill and urged its passage.

The Bangor Democrat and other supporters of the legislation warned that someone would be killed in the prison system unless something is done to ease the crowding.

Blanchette said the state couldn’t continue keeping people in prisons and jails at an annual cost of $37,000 per inmate while doing little to rehabilitate them.

The new legislation calls for a plan of action to address mental illness in the criminal justice system and a policy that gives judges more discretion in making treatment a factor in sentencing.

“Prison officials are just not equipped to deal with inmates that have mental health problems,” said Sen. Ethan Strimling, D-Portland. He serves on the commission and co-chairs the Legislature’s Criminal Justice Committee.

“We need to get these inmates into the [mental health] hospitals where they can get the help they need,” he said,” and we need to make sure those facilities are safe.”

The provision to give judges power to make treatment part of sentencing was opposed by some of the state’s district attorneys, who said the “diversionary sentencing” authority could weaken their authority to strike plea bargains.

Some of the district prosecutors met with the governor a day before he signed the legislation to express their concerns, said spokesman Lee Umphrey.

The governor listened, but did not change his position on a bill that had received strong support from his administration.

Penobscot County Sheriff Glenn Ross said he was pleased the governor is recognizing the seriousness of the situation. He held a news conference last week to spell out the problems at his jail from inmates with both diagnosed and undiagnosed mental health problems.

“When it comes time to fund whatever solution they come up with, I hope that they realize that you pay now, or you pay later, but you will pay,” he said.

As for the new law signed Wednesday, prison crowding will not be eased overnight because the bill is not retroactive and no current offenders will be affected.