Peterson's arrest and subsequent trial received significant American news media coverage until 2005, when he was sentenced to death by lethal injection. He remains on death row in San Quentin State Prison while his case is on appeal to the Supreme Court of California. He maintains his innocence.
On December 24, 2002, Laci Peterson was reported missing from their Modesto, California, home. She was eight months pregnant with a due date of February 10, 2003, and the couple had planned to name the baby boy Conner. The exact date and cause of Laci's death was never determined. Peterson initially reported his wife missing on Christmas Eve, and the story quickly attracted nationwide media interest.
Modesto police did not immediately identify Peterson as a suspect, largely because Laci's family and friends maintained their faith in his innocence during the month following Laci's disappearance. Eventually, police grew more suspicious due to inconsistencies in his story. On January 17, it became known that Peterson had had numerous extramarital affairs, most recently with a massage therapist named Amber Frey. Frey approached police about Peterson, whom she had just begun to date, after discovering he was actually married to a missing woman. At this point, Laci's family announced that they had withdrawn their support of Peterson. They later said that they were angered not by the affair, but that Peterson had told Frey that he'd "lost" his wife and that he would be spending his first Christmas without his wife — 14 days before Laci disappeared. To the Rochas, this meant that Peterson had already planned to kill Laci long before her disappearance.
Frey became a key witness in the case against Peterson when she agreed to let the police tape their subsequent phone conversations in hopes of getting him to confess. Despite this, Peterson was not recorded making any confession to Frey.
Frey told the police that two weeks before Laci's disappearance, Peterson had implied to her that he was a widower by saying that he had "lost his wife." During the trial, the audio recordings of Peterson and Frey's telephone conversations were played, and the transcripts were publicized. Their contents proved to be both revealing and, ultimately, damning to Peterson's character. For example, they revealed that in the days after Laci went missing, Peterson claimed to Amber that he had traveled to Paris to celebrate the holidays, in part with his new companions Pasqual and François. In reality, Peterson made one of these phone calls while attending the New Year's Eve candlelight vigil in Modesto for his missing wife.
Recovery of body
On April 14, 2003, the remains of a fetus washed ashore from San Francisco Bay in Richmond's Point Isabel Regional Shoreline, north of the Berkeley Marina, where Peterson had been boating the day of Laci's disappearance. The next day, a partial female torso missing its hands, feet, and head washed ashore in the same area. The body was identified as Laci Peterson, the fetus as Laci's unborn child. Autopsies were performed, but due to decomposition the exact cause of death could not be determined. The medical examiner did note that Laci had suffered some broken ribs (the 5th, 6th, and 9th ribs) prior to her death; these injuries were not caused by the body's dragging along the rocks in the bay. Prosecutors theorized that Laci may have been suffocated or strangled in the couple's home. The FBI and Modesto Police Department performed forensic searches of the couple's home, Peterson's truck, the tool box in the back of his truck, his warehouse, and his boat.
Peterson was arrested on April 18, 2003, in La Jolla, California, in the parking lot of the Torrey Pines Golf Course, where he said he was meeting his father and brother for a game of golf. At the time of his arrest, Peterson was in possession of the following non-golf specific items:
- approximately $15,000 in cash
- Four cell phones
- multiple credit cards belonging to various members of his family
- an array of camping equipment, including knives, implements for warming food, tents and tarpaulins and a water purifier
- a dozen pairs of shoes
- several changes of clothing
- a T-handled double-edged dagger
- a MapQuest map to Frey's workplace (printed the previous day)
- a shovel
- 2 ropes
- 200 blister packs of sleeping pills
- his brother's driver license and a picture of his wife
His hair and goatee had been dyed blond. Although he claimed the lighter hair color was the result of chlorine from swimming in a friend's pool, the pool's owner later testified that, to his knowledge, Peterson had never swam in his pool nor made use of his hot tub.
Peterson had been represented before his arraignment by Kirk McAllister, a veteran criminal defense attorney from Modesto, California. Peterson told Judge Nancy Ashley at arraignment that he could not afford a private attorney.
Chief Deputy Public Defender Kent Faulkner was also assigned to the case. Peterson later indicated that he could afford a private attorney Mark Geragos, who had done other high-profile criminal defense work. A judge moved Peterson's trial from Modesto to Redwood City, California on January 20, 2004, due to increasing hostility toward Peterson in the Modesto area.
The trial, the People of the State of California v. Scott Peterson, began in June 2004 and was followed closely by the media. The lead prosecutor was Rick Distaso. Geragos led Peterson's defense.
Prosecution witness Amber Frey engaged her own attorney, Gloria Allred, to represent her interests. Allred was not bound by the gag order imposed on those involved in the trial. Although she maintained that her client had no opinion about whether Peterson was guilty, Allred was openly sympathetic to the prosecution. She appeared frequently on television news programs during the trial.
Peterson's defense lawyers based their case on the lack of direct evidence and played down the significance of circumstantial evidence. They suggested that the fetal remains were of a full-term infant and theorized that someone kidnapped Laci, held her until she gave birth, and then dumped both bodies in the bay. The prosecution's medical experts contended that the baby was not full term and died at the same time as his mother. Geragos suggested that a Satanic cult kidnapped the pregnant woman. He also claimed that Peterson was "a cad" for cheating on his pregnant wife but not a murderer.
One juror was removed early in the trial due to misconduct and was replaced, this on a complaint by CourtTV. A videotape showed the juror and Brent Rocha, Laci Peterson's older brother, speaking as they passed one another in the courthouse. Jury foreman and attorney Gregory Jackson later requested his own removal during jury deliberations, most likely because his fellow jurors wanted to replace him as foreman. Geragos told reporters that Jackson had mentioned threats he received when he requested to be removed from the jury. Jackson was also replaced by an alternate. On November 12 the reconstituted jury convicted Peterson of first-degree murder with special circumstances for killing Laci and second-degree murder for killing the fetus she carried. The penalty phase of the trial began on November 30 and concluded December 13 when, at 1:50 P.M. PST, the twelve-person jury recommended a death sentence for Peterson.
Members of the jury stated in later press appearances that they felt that Peterson's demeanor – specifically, his lack of emotion and the phone calls to Amber Frey in the days following Laci's disappearance – indicated he was guilty. They based their verdict on "hundreds of small 'puzzle pieces' of circumstantial evidence that came out during the trial, from the location of Laci Peterson's body to the myriad of lies her husband told after her disappearance." They also decided on the death penalty because they felt Peterson betrayed his responsibility to protect his wife and son.
The only piece of forensic evidence identified was a single hair, thought to have been Laci's, found in a pair of pliers from Peterson's boat.
Peterson changed his appearance and purchased a vehicle using his mother's name in order to avoid recognition by the press. He added two pornographic television channels to his cable service only days after his wife's disappearance; the prosecution suggested that this meant Peterson knew his wife would not be returning home. He expressed interest in selling the house he had shared with his wife, and he sold Laci's Land Rover.
Testimony for the prosecution included Rick Cheng, a hydrologist with the United States Geological Survey, and an expert witness on tides, particularly of the San Francisco Bay. Cheng admitted during his cross-examination that his findings were "probable, not precise"; tidal systems are sufficiently chaotic, and he was unable to develop an exact model of the bodies' disposal and travel. The prosecution explored an affair by the defendant with Amber Frey, and the contents of their taped telephone calls.
The defense suggested a prostitute accused of stealing checks from Peterson's mailbox may have murdered Laci, but Modesto police Detective Mike Hermosa did not indicate that the prostitute was ever a suspect in Laci Peterson's disappearance. Prosecutor Dave Harris noted that the checks were stolen after Laci vanished, meaning the woman was not involved in her disappearance.
Geragos seemed quite confident that Dr. Charles March could single-handedly exonerate Peterson by showing that the fetus Laci carried died a week after prosecutors claimed. Under cross-examination, March admitted basing his findings on an anecdote from one of Laci's friends that she had taken a home pregnancy test on June 9, 2002. "Prosecutors pointed out that no medical records relied on the June 9 date and March became flustered and confused on the stand – and even asked a prosecutor to cut him 'some slack' – undermining his credibility."Summing up this key defense witness, Stan Goldman, a criminal law professor at Loyola Law School in Los Angeles said, "There were moments today that reminded me of Chernobyl." According to one newspaper account about Dr. March's testimony, "But by the end of his testimony Thursday, legal analysts and jurors closed their notebooks, rolled their eyes, and snickered when they thought no one was looking."
The prosecution presented Scott Peterson's affair with Amber Frey and money as a motive for the murder. Prosecutors surmised that Peterson killed his pregnant wife due to increasing debt and a desire to be single again.
On March 16, 2005, Judge Alfred A. Delucchi formally sentenced Scott Peterson to death, calling the murder of his wife "cruel, uncaring, heartless, and callous". The prescribed method of execution was lethal injection. He also denied the defense's request (which was based on evidence of juror misconduct and media influence) for a new trial and ordered Peterson to pay $10,000 toward the cost of Laci Peterson's funeral.
In the early morning hours of Wednesday, March 17, 2005, Peterson arrived at San Quentin State Prison. Peterson was reported not to have slept the night before, being too "jazzed" to sleep, calling some to question his state of mind.  Peterson joined other inmates in California's sole death row facility while his case is on automatic appeal to the Supreme Court of California in San Francisco. National Geographic made a documentary on San Quentin prison, with Scott Peterson's admission to the prison covered in its Part Two.
On July 6, 2012, Peterson's lawyer, Cliff Gardner, filed a 423-page appeal of his sentence.