Stepsister describes last sighting of Laci Peterson
Geragos declares Scott Peterson "stone cold innocent."
Opening defense statements -- from witnesses to meringue.
Prosecutors claim inconsistencies in Peterson's behavior.
REDWOOD CITY, California (CNN) -- Prosecutors began laying out their case against Scott Peterson Thursday with witnesses describing their encounters with his wife, Laci, the last day she was seen alive by anyone other than her husband.
Amy Rocha, Laci Peterson's half-sister, took the witness stand to say she cut Scott Peterson's hair the evening of December 23, 2002. Laci was there with her husband, Rocha testified during the afternoon session of the third day of the much-anticipated double-murder trial.
As the three chatted during the haircut, Rocha said Scott Peterson offered to pick up a fruit basket that she'd ordered for her grandfather the next day because he would be playing golf at a course nearby.
Prosecutors say Peterson also told other people he would play golf on the day of Christmas Eve.
After Laci Peterson was reported missing December 24, Scott Peterson told police he had been fishing in the San Francisco Bay and produced a receipt for parking at the Berkeley Marina.
Rocha also testified that her stepsister wore a black top with cream-colored polka dots, cream-colored pants, a black jacket and a cream-colored scarf.
The hair stylist-in-training recalled that her stepsister, about eight months pregnant, was tired that day.
The owner of the salon, Chris Johnson, testified earlier Thursday about seeing Laci and Scott in the salon that night.
He recalled that Laci was wearing a dark shirt and beige pants.
Peterson is accused of killing his wife and their unborn son. If convicted, he could face the death penalty.
Prosecutors believe Peterson killed his wife the evening of her haircut and disposed of her body in San Francisco Bay. Her body, and that of the baby, washed up separately on the eastern shore of the bay in April 2003, not far from where Peterson said he was fishing the day his wife disappeared.
Laci Peterson's body was clad in beige pants and a maternity bra.
Rocha testified that the black shirt with cream-colored polka dots was found February 18, 2003, when police called her to come to the Petersons' home to look at her stepsister's clothes.
Rocha said the shirt she believes Laci was wearing December 23 was found wadded up in a dresser drawer.
Scott Peterson has said his wife was wearing black pants and a white top when he saw her the next day, the morning of Christmas Eve, before he left to go fishing.
He said his wife was planning to walk their dog.
In testimony earlier Thursday, the owner of a day spa where Laci Peterson had an appointment around noon on December 23 recounted that the pregnant woman was wearing black pants and a white, long-sleeved shirt, and seemed tired during her visit.
Michelle Buer, owner of the Sweet Serenity Day Spa, testified that while women at the spa often complained about their husbands as they were receiving treatments, Laci Peterson never did.
Buer said Laci Peterson also never mentioned that her husband was having an affair.
Scott Peterson initially denied and then admitted having an affair that began before his wife was reported missing December 24. In a television interview a few weeks later, he said Laci Peterson knew about the affair and was "OK" with it.
Rocha said her stepsister never mentioned that Peterson was having an affair.
She also testified that Peterson called her in a panic around 5:15 p.m. on Christmas Eve, asking if she was with Laci.
Rocha told him she wasn't, she recounted, and Peterson said he would call other family members and friends to check with them.
Soon afterward, friends and family members met at the couple's home and began going door-to-door in the neighborhood to ask if anyone had seen Laci, Rocha said.
In his opening statements Wednesday, Mark Geragos, Peterson's defense attorney, said evidence will show that the couple's baby was born alive sometime in January, and that his client is "stone cold innocent."
Peterson could be sentenced to death or life in prison with no chance of parole if he's found guilty on the two murder charges.