Peterson was arrested in San Diego by Modesto Police.
SACRAMENTO, California (CNN) -- DNA tests confirmed Friday the bodies of a woman and a baby boy found in the San Francisco Bay area were those of Laci Peterson and her son.
Peterson, 27, eight months pregnant with a son who was to be named Connor, disappeared from her Modesto, California, hometown on December 24.
Her husband, Scott Peterson, was arrested Friday while driving in San Diego and taken back to Modesto, said police, who admitted they were concerned he might try to cross the border into Mexico.
"There are no other suspects," said Modesto Police Chief Roy Wasden.
"There is no question in our minds that the unidentified female is Laci Peterson and the unidentified fetus is the biological child of Laci and Scott Peterson," said California Attorney General Bill Lockyer.
Lockyer said the chances of the Petersons not being the parents of the boy were in the billions. The Contra Costa County Coroner will make the final formal identification. Laci Peterson was due to deliver her son February 10.
Wasden told reporters Laci Peterson's relatives were "devastated" when they heard the news.
Stanislaus County District Attorney James Brazelton said Scott Peterson likely would be charged with double capital murder early next week, but he said prosecutors would not necessarily seek the death penalty.
The bodies washed ashore Sunday and Monday in separate locations about two miles from the marina at Point Isabel Regional Park on San Francisco Bay, about 80 miles west of Modesto.
A large black tarpaulin came ashore about 60 yards from where Laci Peterson's body was found, although it was not known whether it was connected to the case, said East Bay Region Park Police Chief Norm Lapera.
A passer-by discovered the woman's badly decomposed remains Monday less than two miles away from where those of the baby boy were found the day before.
Forensic teams could not immediately identify the bodies, and Contra Costa County coroner's office called in a forensic anthropologist to examine the remains.
DNA tests were conducted because the body was missing its head, sources close to the investigation told CNN. Without the skull, investigators could not use dental records, the quickest tool in body identification.
Modesto police recently reclassified the Peterson case as a homicide.
Investigators twice searched the Petersons' home, and impounded Scott's car and boat shortly after Laci's disappearance. Police had not called Scott Peterson a suspect in the case.