(CNN) -- It may be December before the second man convicted in a 2007 deadly Connecticut home invasion learns if he will die for his role in a crime that drew worldwide attention.
On October 13, Joshua Komisarjevsky was convicted on 17 charges, including three counts of murder, four counts of kidnapping, and charges of burglary, arson and assault in the deaths of Jennifer Hawke-Petit and her daughters, Hayley Petit, 17, and Michaela Petit, 11.
The sentencing phase of the trial, which is expected to take up to six weeks, began Tuesday. The jury could sentence Komisarjevsky, 31, to life in prison or death.
"This grave and awesome decision will be made by you and you alone," Judge Jon Blue told the jury before giving them preliminary instructions as the trial began.
During an hour-long opening statement, the defense also reminded the jurors of the heavy burden they bear.
"By your verdict, you're guaranteeing that Joshua will receive one of the two harshest penalties, life or death," attorney Jeremiah Donovan said.
Donovan also outlined Komisarjevsky's difficult childhood as he spoke to the jury. According to Donovan, Ben and Judy Komisarjevsky adopted him after he was given up by his biological parents when he was only 2 weeks old.
By the time the child was 4, he had been repeatedly sexually assaulted by a foster child living in the family home.
"Joshua lived in a state of fear," Donovan said. "It was pretty clear by fourth or fifth grade, this was a young man who was deeply troubled."
Komisarjevsky's dad, an evangelical Christian, was described as "rigid" and "difficult" by the defense. Donovan said the family used prayer to deal with the child's behavior issues.
Eventually, according to Donovan, Komisarjevsky and his sister were home-schooled, and by the summer of 1992, the family had "pretty much cut themselves off from anyone who could help them with the crisis they had been dealing with."
The defense went on to say that as a teenager, Komisarjevsky entered a really dark period of his life and began using drugs after he was committed to a mental hospital for depression.
Donovan ended his opening statement to the jury by describing Komisarjevsky as a "damaged lad."
"This young man was ruined pretty much from birth," Donovan said.
But the defense also argued that Komisarjevsky had no history of violence or aggression and had "adjusted to prison life."
"Evidence is going to show that Josh does well in prison." Donovan said.
To win a verdict of death, the state must present evidence to the jury that proves aggravated factors exist in the case beyond a reasonable doubt.
The court doesn't expect to hear closing arguments until after Thanksgiving.
Steven Hayes, the first defendant to stand trial in the case, was sentenced to death in December 2010 after a jury convicted him on 16 of 17 charges.
Both trials were filled with emotional testimony detailing the deaths of Hawke-Petit and her daughters.
Prosecutors had argued that Hayes and Komisarjevsky went into the Petit home, beat and tied up Dr. William Petit, raped and strangled his wife, molested one of their daughters, and set the house on fire before attempting to flee.
The two daughters, who were both tied to their beds, died of smoke inhalation, though William Petit managed to escape.
Before assaulting and killing Hawke-Petit, Hayes forced her to go to a bank and withdraw $15,000 from an account after finding evidence the account held between $20,000 and $30,000, authorities said.
As the verdict was read earlier this month, the victims' family members wept openly.
Petit, the lone survivor, called the verdict "a relief," describing Komisarjevsky as "a lying sociopathic personality."
"I personally felt this case was a case about sexual predation," he said. "There is just a huge plague of violence against women in this country."
He added that he wondered what it would have been like "if I had two sons, instead of two daughters."
Standing sullen-faced before reporters in front of a New Haven courthouse, Petit said he has only "occasional moments of peace."
"It's not clear to me that time heals all wounds ... but you form some scars."
CNN's Brian Vitagliano contributed to this report.