REDWOOD CITY, Calif. – As opening statements began Tuesday in the double-murder trial of Scott Peterson (search), prosecutors started detailing a case they hope will prove beyond a reasonable doubt that Peterson killed his pregnant wife and unborn child.
Prosecutor Rick Distaso told jurors that Scott Peterson called his mother-in-law that afternoon and said he had returned from a fishing trip to an empty house — though he allegedly later told the uncle of his wife Laci that he was golfing all day.
"He says, 'Mom, Laci's missing,"' Distaso told jurors. "Right then, Sharon Rocha (search) knew that things were very seriously wrong."
By nightfall, police and family were investigating a missing person report, which would unfold into the case that captivated the nation.
"It's Christmas Eve, there's a woman who's eight months pregnant who is missing under very mysterious circumstances," Distaso told jurors, over objections from defense attorneys. "They're looking for evidence of a burglary. They're looking for evidence of a robbery. There is nothing out of place."
They did find a loaded .22-caliber handgun in the glove box of Peterson's truck, said Distaso. The gun also was mentioned at pretrial hearings.
Rocha joined investigators in a panicked search of garbage cans at a fog-shrouded park near the couple's Modesto home, where Laci Peterson (search) used to walk the family's golden retriever.
Distaso described Scott Peterson as terse with family and unable to tell police what he had been trying to catch on his fishing trip to San Francisco Bay.
By Christmas Day, Peterson was more engaged and talking in ways that Distaso suggested point to his guilt. For example, he said, Peterson called police to ask if they were using cadaver-sniffing dogs to search the park.
"'We haven't come to the conclusion yet that Laci Peterson is dead,"' Distaso said the officer told Peterson. "That kind of sets the stage for this entire case."
The former fertilizer salesman could face the death penalty or life without parole if found guilty in a trial that is expected to last up to six months.
Prosecutors have had more than a year to prepare their case — which California Attorney General Bill Lockyer called a "slam dunk" on the day authorities arrested Peterson.
But the lack of direct evidence linking Peterson to the murders has turned the case from a sure thing to a spin zone of circumstantial evidence for prosecutors, legal experts say. Prosecutors don't have a murder weapon or even a cause of death.
The main focus of the case is shaping up to be how tight a web the prosecution can spin, and how ably the defense can explain away Peterson's behavior following his wife's disappearance.
On Tuesday, Judge Alfred A. Delucchi gave jurors the standard admonishment that circumstantial evidence cannot lead to a finding of guilt unless the facts "cannot be reconciled with any other rational conclusion."
But circumstantial evidence shouldn't be underestimated, said Bill Sullivan, a former federal prosecutor.
"The jury will be directed that circumstantial evidence is just as compelling as direct evidence," Sullivan told Fox News. "Circumstantial or not, all this evidence can lead to a guilty verdict. It is the collection of circumstantial evidence, it is the totality ... shown time after time, example after example it will point in one direction."
Sullivan said he feels that the prosecution will be able to argue that "Scott had the motive and the opportunity at the exclusion of all others."
The outcome of the case is unpredictable, said Greta Van Susteren, host of Fox News' "On the Record with Greta Van Susteren."
"We do not know what prosecution has in its file because there has been a gag order," she said Tuesday. "I have no clue what's going to happen at the end of this trial, which is why this trial is so fascinating.... There isn't one lawyer in this country that could predict this verdict."
The prosecution is expected to call hundreds of witnesses to argue that any explanation other than Peterson's guilt is simply too outlandish.
"The defense can mainly take comfort in the fact that they do not have a cause of death, and proving guilt beyond a reasonable doubt is very, very hard without that," said Robert Talbot, a professor at the University of San Francisco School of Law.
"What the defense has to overcome is if you look at the whole picture, any other explanation the defendant has for her murder isn't going to be very good."
It is unclear what witnesses will be called because the list is sealed and attorneys are working under a sweeping gag order. Defense attorney Mark Geragos (search) has presented a list of just 18 witnesses, according to a prosecution filing last week.
Authorities allege Peterson, 31, killed his 27-year-old wife in their Modesto home because he was having an affair, then drove her body nearly 100 miles to San Francisco Bay and dumped it from his small boat.
The bodies of Laci Peterson and her fetus, a boy the couple planned to name Conner, washed ashore in April 2003. The site is a few miles from the Berkeley Marina, where Peterson told authorities he set out on a solo fishing trip on the morning of Dec. 24, 2002, the same day he says his wife vanished.
Prosecutors will use many of Peterson's nearly 3,000 telephone conversations that police recorded after his wife's disappearance. Likely among the most damaging, experts say, are calls between Peterson and his mistress, Amber Frey (search), who began cooperating with authorities soon after Laci Peterson vanished.
Peterson was arrested in April 2003, not far from the Mexican border. He was carrying $10,000 and his brother's driver's license and had dyed his hair blond.
Geragos has suggested that a satanic cult may be responsible for Laci's death, and that the killer could have dumped the bodies in the bay after hearing of Peterson's fishing trip account.
It took more than two months to find 12 jurors and six alternates in this county just south of San Francisco, where the trial was moved because a judge didn't think Peterson could get a fair hearing in the couple's hometown.
The Associated Press contributed to this report.