Defense's Turn at Peterson Sentencing Trial

Scott Peterson's defense team began making its case for life imprisonment Wednesday in the penalty phase of his murder trial, a day after his slain wife's mother delivered heart-wrenching testimony about why the former fertilizer salesman should get the death penalty.

In a surprise move, defense attorney Pat Harris gave the opening statement Wednesday, rather than his partner Mark Geragos (search), who took the lead during the culpability phase of the trial.

Harris told the jury that defense testimony could take about a week and asked them to have patience. He said they'd hear from family, friends, co-workers and others about why Peterson's life was "worth saving."

"They're going to talk to you about the fact that this is a man who constantly put others first," Harris said. "We're going to do 30 years of a man's life as opposed to the five months you've heard about. We're going to tell the whole life story."

Harris said much of Peterson's life had been laid bare before the Nov. 12 guilty verdict. But as the second day of the penalty phase began, he told jurors they didn't know the true Scott Peterson (search).

"You don't know who Scott Peterson is, and it's going to be our job to show you," Harris said. "What we're going to now show you is the 30 years that preceded this. And when we show you those 30 years, I believe that you will agree that this is a life worth saving."

Peterson's father, Lee Peterson (search), took the stand Wednesday in his son's defense, and Peterson's mother, Jackie Peterson (search), planned to do the same.

Wearing a white sweater and looking tired, Lee Peterson said his daughter-in-law's death and the subsequent trial of his son have taken a heavy emotional toll.

"I'm frightened, deeply saddened," he said, looking tired on the witness stand. "Losing someone you love and now having our son in such jeopardy — it's just beyond belief."

Asked how he would feel if his son was sentenced to death, he paused and looked toward the defense table.

"I don't even want to entertain that thought," he said. "I just can't imagine anything worse."

Scott's father also talked about his life growing up in Minnesota, moving to California for college and meeting his second wife, Jackie. Each had children before they met, but Scott was their child together.

"She's the best thing that ever happened to me, just a wonderful sweet, woman," he said of Jackie Peterson.

As an infant, Scott Peterson became "very ill" with pneumonia and was placed in a plastic chamber — called a croup tent — that controls humidity, Lee Peterson said.

"It was very risky. The doctor said this may not go so well, but he pulled out of it and he lived," he said.

He recalled a son who in childhood was always smiling, enjoyed playing with trucks and action figures, and liked to snuggle while his father read to him.

Lee Peterson said Scott grew into a good student and school leader. He became captain of his high school golf team, sang at a senior citizens' home on Sundays and tutored younger students.

He described his son as motivated and full of energy.

"You wouldn't catch him laying around in bed," Lee Peterson said.

Peterson's half-sister, Susan Caudillo, called him her "baby brother" and said a death sentence would devastate the family.

"I can't describe exactly how I would go on," Caudillo said, stifling tears. "I know it would kill my parents. I see the pain in their faces every day."

There has been speculation that Peterson himself could testify in an effort to convince jurors that he should not be put to death. On Wednesday, he sat passively beside Geragos as Harris spoke to the jury.

"We're not asking you to let this man go free," Harris told jurors. "Life without parole is not some sort of a holiday."

On Tuesday, Sharon Rocha (search) took the stand, screaming at her former son-in-law that instead of murdering his 8-months-pregnant wife Laci Peterson (search), he could have simply divorced her.

Rocha brought members of the jury panel and those in the courtroom to tears with her testimony, much of which she addressed directly to Peterson, 32, who was convicted of killing his 27-year-old wife and the couple's unborn son.

"Divorce was always an option — not murder!" Rocha shrieked at Peterson, whom she initially defended when Laci was reported missing on Christmas Eve 2002.

Rocha's sudden outburst — during which she stood up from her seat, her voice rising and cracking — made several jurors jump.

The jury will ultimately have to decide between recommending life in prison or death by lethal injection.

FOX News' Claudia Cowan, Catherine Donaldson-Evans, Trace Gallagher and The Associated Press contributed to this report.