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NEW: Dr. William Petit: The death penalty is a highly charged topic, which a dissenting judge recognized

Until this ruling, inmates who were already on death row when the law passed could still have been executed

Among those spared: Joshua Komisarjevsky and Steven Hayes, convicted of 2007 home invasion murders

(CNN) —  

The Petit family home-invasion murders drew international attention: Two men raped and strangled a mother and molested one of her daughters in Connecticut. Then they set fire to the home, killing the woman and her 11- and 17-year-old daughters.

On Thursday, the Connecticut Supreme Court declared the death penalty unconstitutional, sparing the lives of the two killers and nine other convicts who were on death row when the state abolished capital punishment in 2012.

Joshua Komisarjevsky and Steven Hayes were sentenced to death for the slayings of Jennifer Hawke-Petit, 48, and her daughters, Michaela and Hayley.

“I’m not surprised at this decision,” said Michael Dearington, who prosecuted Komisarjevsky and Hayes, declining to elaborate.

In 2012, Gov. Dannel Malloy signed a bill into law that abolished the death penalty, making the state the 17th in the nation to abandon capital punishment and the fifth in five years to usher in a repeal. But inmates already on death row when the law passed were considered exempt from the law and could be executed.

The Supreme Court decision stems from the appeal of a defendant whose lawyers argued that executions carried out after the state abolished the death penalty would represent cruel and unusual punishment. That inmate, Eduardo Santiago, faced the death penalty after being convicted of a murder in West Hartford in 2000 in exchange for a snowmobile.

Related: Why experts say there’s no such thing as ‘humane’ execution

“Upon careful consideration of the defendant’s claims in light of the governing constitutional principles and Connecticut’s unique historical and legal landscape, we are persuaded that, following its prospective abolition, this state’s death penalty no longer comports with contemporary standards of decency and no longer serves any legitimate penological purpose,” Justice Richard Palmer wrote for the majority.

Connecticut’s highest court voted 4-3 to overturn the death penalty.

“In prospectively abolishing the death penalty, the legislature did not simply express the will of the people that it no longer makes sense to maintain the costly and unsatisfying charade of a capital punishment scheme in which no one ever receives the ultimate punishment,” the Supreme Court decision said.

The ruling said the 2012 law “held a mirror up to Connecticut’s long, troubled history with capital punishment: the steady replacement by more progressive forms of punishment; the increasing inability to achieve legitimate penological purposes; the freakishness with which the sentence of death is imposed; the rarity with which it is carried out; and the racial, ethnic, and socioeconomic biases that likely are inherent in any discretionary death penalty system.”

The decision said since such a system “fails to comport with our abiding freedom from cruel and unusual punishment, we hold that capital punishment, as currently applied, violates the constitution of Connecticut.”

In a statement Thursday, Malloy said the state has executed two inmates in the last 54 years. Both volunteered to be executed.

“Many on death row are able to take advantage of endless appeals that cost the taxpayers millions of dollars, and give those convicted killers an undeserved platform for public attention,” said Malloy, a former prosecutor who is opposed to the death penalty.

The governor said the state’s judicial system will seek guidance on the matter but death row inmates “will serve the rest of their life in a Department of Corrections facility with no possibility of ever obtaining freedom.”

“Today is a somber day where our focus should not be on the 11 men sitting on death row, but with their victims and those surviving families members,” he said in the statement. “My thoughts and prayers are with them during what must be a difficult day.”

Hayes was convicted in September 2013 and Komisarjevsky in October 2011.

Hayes’ lawyer, Thomas Ullmann, said he was “totally relieved and thrilled” by the decision.

“Anytime you represent someone and they face the death penalty and you have the prospect of sitting through an execution, it’s a grim responsibility of the lawyer,” Ullmann said. “And we vowed to fight this every inch of the way.”

He added, “Who do we train to save people’s lives? Doctors. Lawyers were trained to protect people’s rights, not save their lives. It’s a responsibility that lawyers never should have had.”

Hayes attempted suicide multiple times after his arrest, a forensic psychiatrist told the court during his trial. In 2010, he told Dr. Paul Amble that he no longer wanted to commit suicide “but intended to let the state do it.”

Ullmann said he hadn’t spoken to Hayes but planned to do so soon.

Komisarjevsky and Hayes entered the Petit family home, beat and tied up William Petit and forced Jennifer Hawke-Petit to go to a bank and withdraw $15,000.They then raped and strangled Hawke-Petit, 48, and molested 11-year-old Michaela before tying her and 17-year-old Hayley to their beds and setting the house afire.

The girls died from smoke inhalation. Their father, Dr. William Petit, managed to escape from the basement.

Petit weighed in on the state Supreme Court’s deth penalty decision, siding against “the four members of the majority (who) disregarded keystones of our governmental structure, such as the separation of powers and the role of judicial precedent.”

“The death penalty and its application is a highly charged topic with profound emotional impact, particularly on the victims and their loves,” Petit said in a statement. “Justice (Carmen Elisa) Espinosa, in her dissent especially, forcefully and compassionately recognizes that devastating impact.”