Updated

NEW HAVEN, Conn. -- A life sentence in prison would actually be harsher than a death sentence for a Connecticut man who killed a woman and her two daughters in a home invasion, because he is so haunted by the crime and isolated in prison, his attorney told a jury Thursday.

Steven Hayes never testified at his trial, but his attorney had him stand up and join him at a podium, face to face with the jury only feet away, as he asked the panel to spare his client from execution. Hayes kept his eyes downcast.

"This is a human being," Hayes' attorney, Tom Ullmann, said during his closing argument. "You may despise what he did. But he's not a rabid dog that needs to be put down."

Hayes was convicted of sexually assaulting and strangling Jennifer Hawke-Petit at her Cheshire home in 2007. Authorities say her daughters died of smoke inhalation after they were tied to their beds and doused with gasoline before the house was set ablaze.

Prosecutors said the crime cried out for the death penalty, saying Hayes and his co-defendant, Joshua Komisarjevsky, tormented the family for seven hours before they were killed. Prosecutors showed a photo of the victims smiling and another photo of a terrified Hawke-Petit at the bank withdrawing money for the men.

Komisarjevsky awaits trial.

"Mr. Hayes and Mr. Komisarjevsky were on a power trip," said prosecutor Gary Nicholson. "They enjoyed the power and control they were exercising over this family."

Nicholson said the victims knew they were about to die.

"In her last moments on this earth as the defendant's hands were choking the life out of her, what was Mrs. Petit thinking about?" Nicholson said. "What were the defendants going to do to her daughters if they were doing this to her."

Nicholson said the girls would have been screaming for their lives.

Defense attorney Patrick Culligan urged jurors to look at the case unemotionally. He emphasized a psychiatrist's testimony that Hayes was in an extreme emotional state triggered by Komisarjevsky telling him the victims were dead after Hayes returned from a bank with Hawke-Petit.

Prosecutor Michael Dearington rejected that argument, saying Hayes knew the girls were still alive when he returned from the bank because he told police he noticed one of the girls had changed clothes.

Prosecutors also rejected defense claims that Hayes was just a follower and Komisarjevsky was the mastermind. They cited text messages the men exchanged the night of the crime in which Hayes said he was "chomping at the bit to get started."

Hayes' attorneys say he repeatedly tried to kill himself in prison after the crime and was deeply remorseful.

"Only Steven Hayes' death can free him from that burden," Ullmann said. "Why would you want to relieve Steven Hayes of that burden?"

Ullmann said Hayes has been kept isolated in prison since the crime and will remain so because other inmates would kill him. He noted that parole had been suspended in Connecticut after the crime.

"If you want to end his misery, you should execute him," Ullmann said. "If you want to end his oppressive and overwhelming conditions of confinement, kill him."

Prosecutors reminded the jury that a prison official testified this week that Hayes indicated he would be fine with a life sentence and that he told her he planned to use his apparent suicidal behavior in prison to show he was remorseful and influence his sentence.

Jury deliberations start Friday.