Scott Peterson (search) has been found guilty of first-degree murder in the death of his pregnant wife Laci, and second-degree murder in the death of their unborn baby boy.

Peterson, 32, stared straight ahead and showed no emotion as the jury announced his fate Friday afternoon. He could face the death penalty or life without parole. The jurors appeared somber, and none seemed to look back at Peterson.

Though the case was based solely on circumstantial evidence, the prosecution managed to convince the six-man, six-woman jury that Peterson meticulously planned to kill his 8-months-pregnant wife to get out of marriage and fatherhood and lead the life of a bachelor again.

The jury handed down the verdict just after 4 p.m. EST Friday after a topsy-turvy week of rocky deliberations and a pair of juror dismissals. The sentencing phase has been scheduled for Nov. 22; the jury will not be sequestered until then, though they remain under a court-imposed gag order. All other parties involved are also under a gag order.

Laci Peterson's mother, Sharon Rocha, broke into loud sobs after the jurors announced their verdict and her son Brent wrapped his arm tightly around her. Tears also flowed from friends of Laci who crowded into the courtroom.

Scott Peterson's visibly upset family left court quickly and without comment.

Outside of the courthouse where the verdict came through a live audio feed, many in the crowd of hundreds smiled and some of them cheered the verdict. Sobs and loud sighs could be heard in the courtroom.

After the jury was dismissed, prosecutor James Brazelton reached forward and patted the shoulder of the lead detective, whose testimony in the case proved pivotal.

As the verdict was read, the jurors unanimously agreed that Peterson planned the December 2002 murder of his wife, 27-year-old Laci Peterson (search), who had been eight months pregnant with their first child. They also unanimously found that he was guilty of murdering without premeditation their unborn baby boy, whom they planned to name Conner.

The former fertilizer salesman was convicted of one count of first-degree murder for killing his wife, Laci, and one count of second-degree murder for killing their nearly full-term fetus.

The verdict came after a five-month trial that was an endless source of fascination to the tabloids, People magazine and the cable networks with its story of an attractive, radiant young couple awaiting the birth of their first child, a cheating husband, and a slaying for which prosecutors had no eyewitnesses, no weapon, not even a cause of death.

The verdict followed a tumultuous seven days of deliberations in which two jurors were removed for unspecified reasons and the judge twice told the panel to start over.

Laci Peterson, a substitute teacher with a radiant smile, made headlines when she disappeared on Christmas Eve two years ago.

Four months later, her headless torso and the remains of her fetus were discovered along the shoreline of the San Francisco Bay about 90 miles from the couple's Modesto home — not far from where her husband claims he was fishing alone the day of her disappearance.

Shortly after the bodies washed ashore, Peterson was arrested in the San Diego area, more than 400 miles from home and not far from the Mexico border, carrying nearly $15,000 and his brother's ID, his hair and goatee dyed reddish-blond.

Police never were able to establish exactly when, how or where Laci died.

Peterson hadn't told anyone he fished or even had bought the small aluminum boat he says he took out on the bay Dec. 24, 2002 — the same boat, the prosecution argued, he used to dump his wife's body, weighted down by homemade cement anchors. In fact, he told relatives a day earlier that he planned to golf that day.

The prosecution argued that Scott Peterson killed Laci because he wanted to escape the responsibilities of marriage and parenthood for a life of freedom with his mistress, Amber Frey, a 28-year-old masseuse and single mother. Lawyers also tried to convince the jury Peterson hoped to gain from a $250,000 life insurance policy taken out on Laci more than a year before she vanished.

But prosecutors had also been plagued by a dearth of concrete physical evidence, which allowed the defense to speculate that Laci was possibly kidnapped and killed by someone else. Earlier in the case they played up a mysterious van that had been seen in the Petersons' neighborhood the day Laci went missing and even floated the theory that members of a satanic cult had abducted the young expectant mother.

The jury was told to return Nov. 22, the Monday before Thanksgiving, to begin hearing testimony on whether Peterson should die by lethal injection or get life in prison without parole. Deliberations on his penalty were expected to begin on or around Nov. 30.

At trial, prosecutors presented 174 witnesses and hundreds of pieces of evidence, from wiretapped phone calls to videotaped police interrogations, depicting Peterson as a liar and a philanderer who was sweet-talking Frey at the same time he was trying to show the world he was pining for his missing wife.

Prosecutor Rick Distaso told the jury that Peterson could not stand the thought of being trapped in a "dull, boring, married life with kids," and either strangled or smothered his wife and dumped her weighted-down body overboard from his fishing boat.

"He wants to live the rich, successful, freewheeling bachelor life. He can't do that when he's paying child support, alimony and everything else," Distaso said. "He didn't want to be tied to this kid the rest of his life. He didn't want to be tied to Laci for the rest of his life. So he killed her."

The jury heard how Peterson had bought a two-day ocean-fishing license days before his wife disappeared, yet claimed his fishing trip was a last-minute substitution for golf because of blustery weather. Prosecutors also offered evidence suggesting he used a bag of cement mix to make concrete anchors to sink his wife's body into the bay.

After a day off for Veterans Day, jurors resumed deliberations Friday at the end of a chaotic week in which the judge removed two members of the panel. The final 12 members deliberated for about 8 hours Wednesday and Friday before reaching their verdict, which the judge prohibited from being broadcast on television.

A huge crowd massed outside the courthouse in Redwood City, where the case was moved after defense attorneys argued Peterson had been demonized in his hometown of Modesto to the point that he couldn't get a fair trial. "He's a sicko. He needs to fry," said Bob Johnston, 42. "I wanted to see that justice was served."

Prosecutors and defense lawyers remain under a gag order that prevents them from commenting.

Peterson never took the stand. His lawyers argued that he was the victim of a frame-up. They suggested that someone else — perhaps homeless people, sex offenders or suspicious-looking characters spotted in the neighborhood — abducted Laci while she walked the dog, then killed her and dumped the body in the water after learning of Peterson's fishing-trip alibi.

Peterson's lawyers also offered evidence that the fetus may have died days or weeks after the disappearance, when Scott was being watched closely by the police and the media.

And they explained his lies and inconsistent statements about his affair and his activities around the time of the disappearance as the mutterings of a man in the midst of a breakdown over his missing wife.

Defense attorney Mark Geragos acknowledged the jurors probably hated Peterson, and pleaded with them not to convict him simply because the prosecution had made him look like a "jerk and a liar."

Geragos also noted the lingering questions about how Laci died. "Maybe the logical explanation for the fact that we have no evidence of her struggling in that house, dying in that house is because it didn't happen in that house," he said.

In addition, Geragos said police found that someone had used a computer in the Petersons' home on the morning Laci vanished — after authorities contend Laci was already dead — to search Web sites for a scarf and a sunflower-motif umbrella stand. He suggested the user was Laci Peterson.

The story proved irresistible to the cable networks, which almost every night brought in experts to pick apart the two sides' legal strategies and expound on some of the soap opera aspects of the case, which included hours of secretly taped calls in which Peterson spun out elaborate tales to Frey.

Frey herself testified, saying that Peterson told her during their affair that he had "lost his wife." But she said that in all their recorded conversations, he repeatedly professed his love for his wife and never said anything to incriminate himself in her slaying.

FOX News' Catherine Donaldson-Evans, Jane Roh, Claudia Cowan, Trace Gallagher and The Associated Press contributed to this report.