Prosecutors said they plan to charge Scott Peterson, 30, with double murder, which would make him eligible for the death penalty.
Officials wouldn't discuss possible motives in the slaying of his pregnant wife, whose body washed ashore earlier this week. Modesto Police Chief Roy Wasden refused to describe the evidence or say how Laci Peterson died, but he said it appeared she was killed the day before Christmas because no "credible witness" saw or heard from her after that.
On Friday, hours before the genetic test results on the bodies were released, plainclothes agents tracking Scott Peterson's movements with phone taps and vehicle sensors pulled him over as he was driving in the San Diego area, where his parents live, and arrested him.
Attorney General Bill Lockyer said they feared Scott Peterson might try to flee, in part due to San Digo's proximity to Mexico. His dark hair was dyed blond and he had a beard a when he was booked into the Stanislaus County jail Friday night. His arraignment is expected early next week.
CBS News Analyst Andrew Cohen says that since Peterson faces capital murder charges, there is no chance that he will be released on bail before trial. That means the case might get into gear sooner rather than later with a preliminary, probable cause hearing -- or mini-trial, if you will -- occurring even before the end of the year.
This could be a death penalty case because police are considering it a double homicide -- that of Laci and her unborn son. That designation offers a tactical advantage for prosecutors because it allows them to look for and get trial jurors who might be more willing to lean toward the government's view of the evidence, Cohen says.
"Clearly investigators had evidence against Scott Peterson before the bodies of his wife and unborn child were found and just as clearly the discovery of those bodies fit into the prosecution's theory of the case as that theory aims toward Scott Peterson," Cohen adds.
The bodies of 27-year-old Laci Peterson and her infant son, his umbilical cord still attached, washed ashore about three miles from where Scott Peterson said he was fishing the morning his wife disappeared.
Wasden said authorities had no other suspects in her death. That a $50,000 reward for information leading to her body remained unclaimed "continued to reinforce that one person knew what happened to Laci and where Laci was" he said.
Peterson's attorney, Kirk McAllister, did not immediately return telephone messages for comment.
The bodies were identified through a comparison with DNA samples from Scott Peterson and Laci Peterson's parents.
"There is no question in our minds that the unidentified female is Laci Peterson. The unidentified fetus is the biological child of Laci and Scott Peterson," Lockyer said. "We're scientifically convinced the match is one in billions."
A spokeswoman for Laci Peterson's family said relatives were devastated by the confirmation of the deaths, but grateful they finally had an answer after months of uncertainty.
"Families in their circumstances will always tell you the worst thing is not knowing," said family spokeswoman Kim Peterson, executive director of the Carole Sund-Carrington Memorial Reward Foundation. "I don't know if relief is the right word. ... The waiting this week has been horrific for them."
From almost the moment his wife was reported missing, Scott Peterson's moves and statements have been scrutinized by authorities.
Modesto police seized his boat, pickup truck and nearly 100 items from the couple's house but had not formally named him as a suspect in his wife's disappearance.
Peterson traded in his wife's Land Rover for a new pickup truck, considered selling their home and eventually admitted an extramarital affair with a massage therapist while his wife was pregnant with the couple's baby.
Shortly after, Peterson said he'd told his wife about the affair in the days before she vanished.
"It was not a positive, obviously ... but it was not something that we weren't dealing with," he told ABC's "Good Morning America." "It wasn't anything that would break us apart."
The affair turned Laci Peterson's family against the son-in-law they had earlier supported. They begged him to cooperate with Modesto police, who had labeled him "uncooperative."
Scott Peterson, a fertilizer salesman, launched his own search effort, separate from the one organized by his wife's family and sanctioned by police. At one point, as searchers looked in the San Francisco Bay and around Modesto, Scott Peterson showed up in Los Angeles to distribute fliers to volunteers at a local hotel.
"We simply have to expand the geographical area," he said at the time.
In February, Scott Peterson told MSNBC he missed his wife and the son she had already named Conner. She was eight months pregnant when she disappeared.
"I can't drive. I can't sleep," he said then. "Sometimes I feel I just can't do it. I feel like I'm in a dark corner and I just can't function."