Scott Peterson (search) was "very gracious" to a newcomer at his high school years ago, the man testified Thursday in a bid to show why his friend should be spared the death penalty.

Aaron Fritz said he first met Peterson about 17 years ago when he moved from Indiana to San Diego to begin high school and joined the golf team.

"I think he realized I was new to the area and new to the school ... He was very gracious and very welcoming and always invited me to have lunch with his friends and just kind of made me feel welcome," Fritz said.

Testifying on the third day of the penalty phase of Peterson's murder trial, Fritz at one point paused, looked over at Peterson seated at the defense table and gave a half smile for several seconds.

Defense attorneys are trying to persuade jurors to sentence Peterson, 32, to life without parole rather than death for the December 2002 slaying of his pregnant wife, Laci. The same jury convicted him of first-degree murder last month in her death and of second-degree murder in the death of the fetus.

"You don't know who Scott Peterson is, and it's going to be our job to show you," defense lawyer Pat Harris told jurors in his opening statement Wednesday.

Peterson occasionally dabbed his eyes with tissue as his father, Lee Peterson, and half sister, Susan Caudillo, that he used to sing for senior citizens on Sundays and worked his way through college.

"I'm frightened, deeply saddened," Lee Peterson testified. "Losing someone you love and now having our son in such jeopardy — it's just beyond belief."

Caudillo called Peterson 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."

Lee Peterson looked tired but maintained his composure, a stark contrast from Laci Peterson's (search) mother, Sharon Rocha (search), who sobbed uncontrollably at times when she testified Tuesday for the prosecution.

Prosecutors are seeking the death penalty. They say Peterson killed his wife on or around Dec. 24, 2002, then dumped her weighted body into San Francisco Bay. The remains of Laci, then 27, and the fetus were discovered four months later along a shoreline a few miles from where Scott Peterson claims to have been fishing alone the day his wife vanished.

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