A Connecticut man convicted of murdering a woman and her two daughters in a home invasion will try to avoid the death penalty by arguing that executions cost taxpayers more than life sentences.

Attorneys for Steven Hayes filed papers Friday in New Haven Superior Court saying they intend to call an expert who would testify that carrying out a death sentence far exceeds the cost of a life sentence.

Dr. William Petit, the lone survivor of the home invasion, said he will not submit a victim impact statement during the hearing. Petit said that while state law guarantees his right to make such a statement, it is so vague that it fails to make clear whether the statement can be read before the jury reaches a decision on life or death.

He fears that an appellate court might decide that the way the statement was made did not conform with the law.

"This lack of clarity in the law is a crippling disincentive to surviving family members of victims in capital murder cases," he said in a statement.

Hayes' attorneys said Hayes repeatedly offered to plead guilty before the trial to all charges in exchange for a life sentence. They want to call the expert "to counter the popular impression that the cost of executing someone saves the state money in comparing to imposing a life sentence without the possibility of release."

Prosecutors objected, saying the cost of an execution is irrelevant to whether Hayes should receive the death penalty.

A jury on Tuesday convicted Hayes of the home invasion in Cheshire in 2007. Starting Oct. 18, the same jurors will begin hearing evidence of whether he should be executed and will decide his punishment by weighing mitigating and aggravating factors.

The argument over costs would be cited as a potential mitigating factor.

Studies show death penalty cases cost an average of $3 million, including lawyers' fees, appeal costs and incarceration, compared with about $1 million for life prison sentences, according to Richard Dieter, executive director of the Death Penalty Information Center, which is critical of how capital punishment is applied.

Most of the cost studies have been conducted by death penalty opponents, said Kent Scheidegger, legal director of the Criminal Justice Legal Foundation and a death penalty supporter. He said he doesn't dispute that executions probably cost more, but said that's because of appeals he views as excessive.

"The murderers are kept on death row way too long," Scheidegger said.

Courts have generally rejected attempts by defense lawyers to raise the cost issue during penalty hearings, Scheidegger said. Such hearings are designed to distinguish which defendants should receive death sentences, not to make arguments about cost or other issues that apply to all cases, he said.

Hayes' attorneys said they also are prepared to call another expert to discuss conditions of confinement "to counter the popular assumption that imprisonment for a violent crime leads to violence during the term of imprisonment."

Prosecutors filed court papers Friday citing the aggravating factors they plan to argue, including that Hayes committed the killings in an especially heinous, cruel or depraved manner. Prosecutors also said Hayes killed during the commission of a felony he had previously been convicted of eight times: third-degree burglary.

Authorities said Hayes and another ex-convict, Joshua Komisarjevsky, broke into a Petit's house, beat the doctor with a baseball bat and forced his wife, Jennifer Hawke-Petit, to withdraw money from a bank before Hayes sexually assaulted and strangled her.

Their daughters, 11-year-old Michaela and 17-year-old Hayley, were tied to their beds with pillowcases over their heads and doused with gasoline before the house was set ablaze, according to testimony. Michaela was sexually assaulted. The girls died of smoke inhalation.

Hayes was convicted of 16 counts, including six capital felony charges, three murder counts and two charges of sexually assaulting Hawke-Petit.

Komisarjevsky's trial starts next year.


Associated Press writer Pat Eaton-Robb in Hartford, Conn., contributed to this report.