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 gunpowder 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.
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 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 the 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.
On Monday, Laci Peterson's friends testified that her pregnancy made her too unsteady to walk the dog.
Laci Peterson's prenatal yoga instructor took that one step further.
"She could barely walk ... she was in pain ... she needed help getting back to the car," Debra Wolski said.
On Tuesday, however, Judge Alfred A. Delucchi cast some doubt on that testimony. Lawyers for both the prosecution and defense agreed that Wolski never told either side that before, the judge told jurors.
By Brian Skoloff
By Brian Skoloff