Detectives removed some 40 paper bags of possible evidence from the house and then sealed it off, prohibiting Peterson from entering until they complete their search Wednesday, even though the 30-year-old fertilizer salesman was not considered a suspect.
"Scott's status in this case of his wife's disappearance has not changed," the police department said in a statement late Tuesday. "He has not been identified as a suspect nor has he been eliminated from this investigation."
Police declined comment on what they were looking for Tuesday and said they wouldn't make any statements barring a major break in the case, which began after Laci Peterson disappeared from the couple's home sometime during the day Dec. 24, according to her husband's account.
The middle-class Covina Avenue residence was searched Dec. 27, at which time unspecified evidence was seized for apparent forensic testing. Police would not elaborate on what new information they had used to obtain the latest search warrant from a judge.
They simply called the search a "follow-up" to the original warrant.
"Discoveries during the Laci Peterson investigation have necessitated revisiting the Peterson residence with a second search warrant," said Craig Grogan, the lead investigator in the case. "Mr. Peterson was cooperative with us this morning. He took some personal and work-related items from the home and left the home voluntarily while the search took place."
Police seized and inventoried the bags of unidentified evidence during the all-day search and also drove off with Peterson's white Dodge pickup truck ostensibly to search for additional evidence.
Laci Peterson, 27, was more than eight months pregnant when she was reportedly last seen the morning of Christmas Eve. Scott Peterson told police his wife had planned to take the couple's dog for a walk along a nearby trail while he spent the day fishing alone on San Francisco Bay some 60 miles to the west.
Peterson said he could not reach his wife by cell phone that afternoon and she was missing when he returned. The dog was found that day by a neighbor with its leash attached to its collar.
Scott Peterson has not been charged in his wife's disappearance, although Laci Peterson's relatives dropped their public support for him after a Fresno woman confirmed that she had been having a monthlong affair with Peterson at the time Laci Peterson went missing. She said she did not know that he was married.
Peterson further angered his in-laws in late January when he traded in his wife's sport utility vehicle, but Laci Peterson's family was able to retrieve the vehicle from the dealer.
Laci Peterson had been due to give birth to her first child on Feb. 10. Scott Peterson's mother, Jackie Peterson, this week said she suspected someone had kidnapped Laci Peterson with the intention of taking the baby once it was born.
"I feel now that they are just harassing Scott and making it impossible for him to even search for Laci like he would like to be doing," Jackie Peterson, from San Diego, told MSNBC on Monday. "It's making it impossible for him to hold his job, and yet they stand there and say he's not a suspect and that he has cooperated. Those two don't go together."
(Reported by Hil Anderson in Los Angeles.)