He was a philandering husband convicted of the shocking murder of his young and very pregnant wife.
"I signed the document that the jury found for death and I think about that a lot," said Fred Castagna, who served as jury foreman. "It was emotional during deliberations, but I don't lose sleep over it."
If the experience of Castagna and others involved in death penalty cases is any guide, the jurors in Peterson's murder trial will have to grapple with raw and deep religious, moral and legal issues as they decide whether he lives or dies.
Arguments in the penalty phase are scheduled to begin Tuesday, but experts say many of the jurors may already have made up their minds about what punishment the 32-year-old former fertilizer salesman deserves.
Jurors who have sent people to death row say even though they were overwhelmingly convinced of their guilt, settling on the death penalty was one of the toughest decisions of their lives.
"I have strong religious beliefs and this wasn't like I had to decide what kind of ice cream to buy," said Brian Bianco, who served as foreman of the jury that convicted Richard Allen Davis of kidnapping and killing 12-year-old Polly Klaas.
Nevertheless, like Castagna, Bianco said he has never doubted that he made the right decision in sending Davis to death row after four agonizing days of deliberations.
It took a jury just 70 minutes to condemn Garton, who was convicted of hiring a hit man to kill his 29-year-old pregnant wife.
"There wasn't any real reason to mull it over," Castagna said. "It was pretty clear that this guy was evil, that he had concocted this scheme to get his wife killed. "
Garton, convicted of two first-degree murder charges, is one of three men in California sentenced to die because a fetus perished during a slaying. Peterson could be the fourth.
Castagna said the five months of sometimes graphic testimony during the guilt phase of the trial "pretty much drove" the death verdict.
"You can't help but consider the fact that you'll have to decide punishment if you find him guilty," Castagna said. "That's always in the back of your mind, but you try not to let it influence you."
Determining punishment before deliberations in the penalty phase is a common experience for many death penalty jurors, according to an ongoing study by the Capital Jury Project at Northeastern University. About half the 1,300 capital case jurors questioned for the study said they had made their sentencing decisions during the guilt phase of the trial, according to chief investigator William Bowers.
"That's perhaps the most profound thing we found," said Bowers, who sometimes serves as an expert witness for those facing the death penalty. "That's a major departure of how it's supposed to work. You're supposed to wait for instructions."
What's more, Bowers said that many jurors vote for death because they fear the killer will someday be set free, even if a sentence of life without parole is an option, as it is in the Peterson case.
"There's a pervasive anxiety that the defendant will be back on the streets," Bowers said.
That anxiety played a major role in the 1988 death sentence of William Dennis, who was convicted of the Halloween night machete slashing of his ex-wife and her eight-month-old fetus as the victim's 4-year-old daughter cowered behind a couch.
"What it came down to for us was that we were not convinced that life without the possibility of parole meant that," said jury foreman Forrester Sinclair. "We decided we had to have him removed from society forever."
Peterson faces death or life in prison without parole for the murders of his wife Laci and the fetus she carried. His lawyer has asked the California Supreme Court for a new jury and a change of venue for the trial's penalty phase. An appeals court turned down the request last week.