Laci's Mom: I Was Suspicious

Scott Peterson had seemed the perfect gentleman to his mother-in-law, so she grew worried when she said he began behaving strangely the moment he first reported his wife, Laci, had vanished.

Laci Peterson's mother, Sharon Rocha, began to cry on the witness stand as she told of her last phone conversations with her murdered daughter, reports CBS News Correspondent John Blackstone.

Rocha, vividly remembered a Christmas Eve telephone call from her son-in-law, a conversation she recounted Monday at Peterson's capital murder trial.

"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 back yard with the leash on and Laci was missing."

The fact that Peterson used the word "missing," instead of saying his wife wasn't there, alarmed Rocha. "I knew something was wrong," she said.

If the jury believes her, this will be damaging testimony, Court TV's Beth Karas told CBS News Early Show co-anchor Hannah Storm.

"This woman knows her son-in-law and expected a certain type of reaction from him and he was avoiding her hugs," Karas said. "He wasn't looking at her. A few days later when they had a candlelight vigil for Laci and over 1,000 people were attending, the parents were on the stage. There was no Scott."

Rocha's day on the witness stand extended testimony from members of Laci Peterson's family. The trial was set to resume Tuesday with Ron Grantski, Laci Peterson's stepfather, testifying as a prosecution witness.

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

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

The remains of Laci Peterson and her fetus, a boy the couple planned to name Conner, washed ashore in April 2003 — not far from where Peterson claims to have been fishing.

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

Rocha said she later asked Peterson what Laci's plans for the day had been. She said Peterson told her Laci had planned to go shopping and come home and make gingerbread before walking the dog. Prosecutors maintain Laci stopped walking the dog weeks earlier at her doctor's request after she suffered spells of dizziness.

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

She said Laci never spoke of any problems in her relationship and appeared to be happy. And she acknowledged that — even though she and a doctor had advised Laci to stop walking the dog — Laci may have continued doing so without telling her.

"Would you describe Laci as headstrong?" Geragos asked.

"That would be fair," Rocha replied.

The jury heard for the first time that Amber Frey was not the only woman with whom Scott Peterson had an affair, reports Blackstone. It happened early in Laci and Scott's marriage but Laci never told her family.

That could be a key point for the defense: "Laci never told her mother about that indiscretion so perhaps she indeed knew about Amber Frey" — as the defense contends — "and wasn't telling her mother about that affair either," said Karas.

"Scott has said publicly he told his wife in early December about Amber Frey," said Karas. "Her friends and family said 'we never knew it. Laci would have told us.'"

Maybe not.

"It was a really compelling day, perhaps one of the strongest in the trial," said Karas.