Scott Peterson (search) was "calm, cool, relaxed" after his wife was reported missing on Christmas Eve in 2002, according to the first detective called to the couple's home for a "suspicious missing person" report.

Detective Allen Brocchini testified Tuesday that Peterson did not appear distraught that his wife, Laci, was nowhere to be found.

Also Tuesday, jurors heard for the first time Scott Peterson's own account of what he did that Christmas Eve day, as prosecutors played a videotaped police interview at his trial that had been made Christmas Day.

Appearing tired but calm, Peterson recounted to Brocchini what happened after he left home for a fishing trip -- expecting that his wife would have walked their dog and baked gingerbread cookies in his absence.

The interview had the tone of an interrogation, and climaxed with police testing his hands for gun powder residue.

Prosecutors allege that Peterson, 31, murdered his pregnant wife in their Modesto home on or around Dec. 24, 2002, then used the fishing story as a cover-up to hide that he had dumped her body into San Francisco Bay (search).

The defense argues that investigators focused on Peterson too quickly to the detriment of other leads. They have asserted that someone else abducted Laci Peterson (search) while she walked their dog.

Brocchini was the first detective at the home, summoned after several officers who had spoken briefly with Peterson deemed his story "suspicious" and requested an investigator.

On the video, Peterson gave often-muffled responses to Brocchini.

He told the investigator that he fetched the boat from his warehouse in Modesto where he also e-mailed his boss, then drove to the bay.

After launching from a marina in Berkeley, he trolled around near an island about a mile from the dock and gave up after about 90 minutes without a catch. He then drove back, stopping for gas and dropping off the boat before returning to an empty home, he said.

Once back, according to the taped interview, he threw the jeans and T-shirt he was wearing into the washing machine, ate some pizza and jumped in the shower.

The fact that Peterson showered so soon after coming home "concerns me the most," Brocchini told Peterson. "That bothers me."

"What concerns me most is doing anything I can," Peterson replied, in an apparent reference to locating his wife.

After the shower, he checked phone messages and then called Laci's parents, who said they hadn't heard from her.

Christmas Eve dinner was set for 6:30 p.m. Before long, Peterson was calling friends and neighbors, then canvassing the streets and park in their neighborhood in a fruitless search.

Laci Peterson's fetus, a boy the couple planned to name Conner, washed ashore April 13. Laci's body washed up from the bay a day later.

Defense lawyers assert that someone abducted her, then framed her husband after hearing his widely publicized alibi of having gone to the bay. They say authorities conducted a sloppy investigation rife with inaccurate reports as they hounded Peterson -- the man they suspected from the start.

Questioned by prosecutors, Brocchini said his role in the investigation was "to find Laci" and "to eliminate Scott Peterson as a suspect."

That task became increasingly difficult, Brocchini said, because of Peterson's behavior.

The day after his wife vanished, Peterson called Brocchini to check on the search.

"He wanted to know if we were using cadaver dogs. I told him we hadn't even considered Laci dead yet," the detective said.

In late December, Brocchini said police learned of Peterson's affair with massage therapist Amber Frey, then two months later determined that Peterson was going to visit her in Fresno.

Brocchini tailed him, but Peterson recognized him.

"I said, 'You've got some explaining to do.' ... I said he wasn't acting like somebody that misses his pregnant wife," Brocchini said.

Brocchini described Peterson as "emotionless, matter of fact, just calm," before he walked away from the detective.

In another development, Judge Alfred A. Delucchi cast doubt on the testimony of a prosecution witness.

Laci Peterson's prenatal yoga instructor, Debra Wolski, testified Monday that Laci "could barely walk" in the days before she vanished -- indicating she would not have walked the couple's dog on Christmas Eve.

Delucchi told jurors Tuesday that lawyers on both sides agreed Wolski never told anyone that story before.