Trial begins for woman charged with husband's stabbing murder at Woodland Hills home

LOS ANGELES (CNS) -- A prosecutor told jurors Friday that a woman who had been carrying on an affair behind her husband's back was the "mastermind" behind his stabbing death and was the only one who knew the narrow time frame that the prominent hairdresser would be alone at the couple's Woodland Hills home.

Monica Sementilli, now 53, is charged with murder and conspiracy in connection with the killing of her 49-year-old husband, Fabio Sementilli, in his back yard on Jan. 23, 2017, shortly before the couple was set to celebrate their 20th wedding anniversary.

Co-defendant Robert Louis Baker -- who was described by Deputy District Attorney Beth Silverman as a registered sex offender who was Sementilli's "lover" -- pleaded no contest in July 2023 to first-degree murder and conspiracy to commit murder.

Baker, now 62, also admitted the special circumstance allegations of murder for financial gain and murder while lying in wait. He was immediately sentenced to life without parole, and Sementilli could face the same sentence if she is convicted of the same counts and allegations.

The prosecutor said Baker is expected to be the defense's "star witness," but told jurors that he has provided "at least a dozen different versions" of what happened to try to fit the evidence. She said the panel would hear recorded conversations between Sementilli and Baker in a courthouse lockup in which Baker said he was going to lie and take the blame.

One of Sementilli's attorneys, Leonard Levine, told reporters after Baker's plea that the defense was confident that his plea and his "truthful testimony will finally establish once and for all that Monica Sementilli had nothing to do with the planning or the murder of Fabio Sementilli, her husband. And we're looking forward to the trial, which we believe will establish that fact."

The defense is set to give its opening statement Tuesday after the prosecutor finishes her opening statement.

A third defendant, Christopher Austin, who was arrested late last year following a lengthy investigation by Los Angeles police, pleaded guilty earlier this month to second-degree murder. The now 39-year-old man agreed to testify truthfully in exchange for a 16-year-to-life state prison term.

With new District Attorney Nathan Hochman among those in the downtown Los Angeles courtroom for a portion of the prosecution's opening statement, Silverman told the panel, "Lust, greed, betrayal, that's what this case is about."

The prosecutor called the victim's killing the "senseless slaughter of a thoroughly innocent and decent human being," and said jurors would learn about his wife's "lies and her deception, her manipulation."

"... He had no idea what's going on behind his back ... He never saw what was coming," the prosecutor said of the victim, saying that one of the couple's two daughters found Baker sleeping in Sementilli's bed on one occasion.

Silverman said the woman sent hundreds of naked photos of herself to Baker during their affair, in which they were "also swinging with other people" while she was simultaneously "living two lives." Divorce wasn't an option for the woman, who came from an Italian Catholic family and "liked to live well" as the wife of a Canadian celebrity hairstylist-turned-Wella company executive, according to the prosecutor.

"She and Baker decided Fabio was getting in the way," the prosecutor said, noting that financial gain was one of the motives in the case.

Silverman showed jurors a photo of Sementilli's "own words written in lipstick" on a mirror -- "Mrs. Baker," and said the defendant also used "Mrs. Baker" in several jailhouse letters she subsequently wrote to her co- defendant while behind bars.

Sementilli used an encrypted app to communicate with Baker before the killing and was able to monitor her home surveillance remotely from her phone, the prosecutor said, telling jurors that it made it possible for the woman to set up the timeline for her husband's killing and ensure that he was the only family member home then.

"She was the mastermind," the deputy district attorney told jurors, noting that the slaying wouldn't have happened without the defendant.

Silverman told jurors that authorities learned during an interview with Austin after his arrest that Sementilli had called Baker to inform him that she was going to send her husband out to pick up dinner the night Austin flew into town from Alaska.

"They decide that Austin is going to murder Fabio at this location," the prosecutor said, telling the panel that Sementilli and Baker exchanged 69 encrypted messages during a 2 1/2-hour period and that Austin subsequently got nervous "because he's not a criminal" and failed to do the job on his own.

The prosecutor said Austin subsequently told authorities that Baker told him that Sementilli wanted it to happen quickly and that the two men would go together to kill her husband the next day.

Austin told authorities that Baker told him that Sementilli would figure out how to get the victim alone, and that he and Baker attacked while seeing the victim smoking a cigar on his back porch.

"Fabio tried to yell, but Baker covered his mouth," the prosecutor said, telling authorities that Austin said Baker stabbed the victim twice and that Austin stabbed him once.

Baker subsequently tried to make the killing look like a robbery gone bad, but only ransacked the couple's master bedroom and left the victim's Rolex watch on his wrist, according to the prosecutor.

The defendant let her teenage daughter return home first, where the girl discovered her father's bloody body and made a frantic 911 call, while the victim's wife tried to distance herself from the killing and then "set out to play the grieving widow," the deputy district attorney said.

Sementilli quickly began efforts that night to try to claim the proceeds from her husband's life insurance policy, for which she has never been paid, Silverman said. She told police that she didn't even think he had life insurance, and then repeatedly called Los Angeles Police Department homicide detectives trying to get information and to "throw law enforcement off the trial that leads to her lover and herself," according to the prosecutor.

The deputy district attorney told jurors that Baker "didn't belong" at the victim's wake at the home less than a week later and "just a few feet away from where Fabio was gruesomely murdered."

Sementilli subsequently behaved as if there was no danger after her husband's killing and left her teenage daughters home alone while she went out with Baker, according to the prosecutor.

Silverman noted that Sementilli would be able to collect her husband's life insurance proceeds if Baker claims that she wasn't involved in the crime and Sementilli winds up being acquitted of the killing.

Sementilli and Baker were arrested by Los Angeles police in June 2017 and charged with murdering her husband, with a conspiracy charge subsequently being added against them. The two were indicted just over two months later on the same charges, and have remained behind bars.