Laci Peterson's (search) mother testified Monday that her son-in-law avoided friends and family as a frantic search got under way for his wife on the evening he reported her missing, and he didn't answer a question about where she might be.

Sharon Rocha (search) said Scott Peterson seemed distant as the two searched for his missing wife in a park near the couple's Modesto home.

"I kept calling out his name and he never did turn around to acknowledge that I was calling him," Rocha said, recalling that she saw Scott Peterson (search) about 30 feet away from her in the park where his wife typically walked the couple's dog.

"I was yelling out to him. ... I was very upset. I was anxious. I was looking for Laci," she said. "Scott never did acknowledge that I was yelling his name."

Not long after, Rocha said she approached Peterson in the park.

"I'm thinking that's when I asked him, 'Where do you think she is?'" Rocha said. Peterson did not respond, she said.

Peterson is accused of killing his pregnant wife in their Modesto home on or around Christmas Eve morning 2002. Prosecutors say he then drove her body to San Francisco Bay (search) and dumped it from his small boat.

Lawyers for Peterson, who says he was fishing alone on the bay that morning, speculate that someone abducted his wife while she walked in the nearby park and then framed him after learning his alibi.

The remains of Laci Peterson and her fetus washed ashore in April 2003 -- not far from where Scott Peterson claims to have been fishing.

Peterson, 31, could face the death penalty or life without parole, if convicted.

Rocha said she again tried to approach Peterson the evening after the search as friends and family gathered at the Petersons' home.

"I was walking over to give him a hug because I thought that we were all upset ... and his family wasn't there," Rocha said. "I was never able to do that ... because he kept angling away from me."

She said she later asked him what his wife's plans for the day had been. She said he told her that Laci Peterson had planned to go shopping and come home and make gingerbread before walking the dog in the park.

Prosecutors maintain Laci Peterson stopped walking the dog weeks earlier, at her doctor's request, after she suffered spells of dizziness.

Scott Peterson told Rocha he had been fishing that morning, she said.

Rocha cried on the witness stand as she described a conversation with her daughter about her last prenatal doctor's appointment. Rocha paused to swallow and took a deep breath before she continued, describing a close relationship with her daughter.

Rocha said they talked on the phone nearly every day and saw each other at least once a week.

She also recalled the telephone call she received from Scott Peterson on Dec. 24, 2002, at 5:15 p.m.

"He said, 'Hi mom.' He said, 'Is Laci there?'" Rocha said. "I said, 'No,' and he said that her car was in the driveway and the dog was in the backyard with the leash on and Laci was missing."

The fact that Peterson used the word "missing" -- instead of saying his wife wasn't home -- alarmed Rocha. He had returned just an hour earlier.

"I knew something was wrong," she said.

Rocha remained calm through most of the day, appearing straight-faced and even-toned in her answers. But at times, she was terse with defense lawyer Mark Geragos (search).

She said Laci Peterson never spoke of any problems in her relationship and appeared to be happy.

She acknowledged that even though she and her daughter's doctor had advised her to stop walking the dog, Laci Peterson may have continued doing so without telling her.

"Would you describe Laci as headstrong? Would that be a fair description?" Geragos asked.

"That would be fair," Rocha replied.

Rocha also acknowledged that she learned only after her daughter died that Laci Peterson knew about an affair Scott Peterson had in the mid-1990s. She said her daughter was a private person.