Defense lawyers are trying to persuade jurors to spare Scott Peterson's life with testimony about his childhood and how a death sentence would affect his family members' lives.

As the penalty phase of the trial began last week, Peterson's friends and family described the convicted murderer accused of killing his pregnant wife, Laci, as a loving son and generous person, someone who never laid a hand on anyone.

After losing its bid for an acquittal, Peterson's defense team was expected to call at least 20 additional witnesses to testify in the next three days, beginning Monday.

Legal experts say Peterson's defense is using a well-planned strategy to persuade jurors to spare his life by sentencing him to prison without parole.

"I think they're basically asking the jury to identify not with Peterson but with the people who care about him," Loyola Law School professor Laurie Levenson said.

But a former prosecutor says the strategy could backfire.

"In the end, if jurors really believe he did it, then every day the defense puts on evidence of him being harmless and kind and patient, it makes Laci look like an even more vulnerable victim," said Jim Hammer, a former San Francisco prosecutor who has been following the murder trial.

Peterson was convicted in November of first-degree murder in the death of Laci and second-degree murder for the death of her 8-month-old fetus.

Prosecutors claim Peterson smothered or strangled Laci in their Modesto home on or around Christmas Eve 2002, then dumped her weighted body into San Francisco Bay.

The remains of Laci and the fetus were discovered about four months later along a shoreline a few miles from where Peterson claims to have been fishing alone the day his wife vanished.