By TERRI VERMEULEN KEITH

A key prosecution witness who testified in the trial of a woman convicted of masterminding her husband’s murder shortly before the couple would have celebrated their 20th wedding anniversary was sentenced to 16 years to life in state prison Tuesday for his involvement in the killing.

Christopher Austin — who was working as a parole and probation officer dealing with at-risk youths in Oregon at the time of his arrest last year — pleaded no contest in January to second-degree murder in the Jan. 23, 2017 stabbing death of Fabio Sementilli, 49, in the backyard of the Woodland Hills home the prominent hairdresser shared with his wife Monica and their two daughters.

Monica Sementilli’s lover, Robert Louis Baker, now 63, pleaded no contest in July 2023 to first-degree murder and conspiracy to commit murder and admitted the special circumstance allegations of murder while lying in wait and murder for financial gain. He is serving a life prison sentence without the possibility of parole.

Baker, a convicted sex offender and former adult movie actor who was called to the stand during the defense’s portion of Sementilli’s trial, maintained that the mother of two had nothing to do with the plan to kill her husband. He said he murdered his lover’s husband because he “wanted her to be around me and with me more — like all the time.”

Sementilli cried after being convicted April 11 of first-degree murder and conspiracy to commit murder, with jurors finding true the same special circumstance allegations of murder that Baker had admitted. She is facing life in prison without the possibility of parole, with sentencing set June 23.

“It’s truly tragic, truly tragic,” Los Angeles County Superior Court Judge Ronald Coen said before imposing the sentence on Austin.

The couple’s oldest daughter, Gessica, said she and her sister are “so disappointed” that Austin was given a plea deal.

“We are the ones who lost a father. We are the ones who lost a mother,” she said.

The couple’s youngest daughter, Isabella, who found her father’s body, spoke directly to Austin during the sentencing, saying that he had “the audacity to cry on the stand” and was a “coward stupid enough to blindly trust someone like Robert Baker.”

“… I will fight for you to rot in prison the rest of your life,” the victim’s youngest daughter said.

Both of the daughters — who left the downtown Los Angeles courtroom before the sentence was handed down — have steadfastly maintained that their mother is innocent of the crime.

In a statement read in court on her behalf, Loretta Picillo said she believes that her younger brother’s killing was “carefully planned and premeditated,” and said their mother “never recovered from the grief.”

“You are a murderer. You are a monster,” she said, directly addressing Austin.

Another of the victim’s sisters, Mirella Sementilli, also addressed Austin in a statement read in court on her behalf, saying that her family had been “traumatized by your choice to say nothing.”

“You chose to be present. You chose to take part,” she said. “There will never be forgiveness, never.”

The victim’s nephew, Daniel Picillo, told Austin, “You ended a good man’s life for nothing, nothing … I hope your soul never knows peace.”

Stephanie Avola, who described herself as the victim’s niece by marriage, said her uncle was brutally murdered in his own backyard and had no idea that those would be his final moments or that the “mastermind behind this horrific act” was his own wife.

“The betrayal is beyond comprehension,” she said, noting that Austin “could have been our family’s hero” if he had stopped the killing from occurring.

Austin, 39, did not address the victim’s family in court, but penned a handwritten note that was given to some of them after the sentencing.

He testified March 4 that Baker told him Sementilli wanted her husband dead, but acknowledged that he did not personally speak to her about the crime.

After his arrest, Austin told a jailhouse operative that “she was supposed to get a lot of money if we did it,” saying Baker — whom he considered “family” — told him that she was “loaded” and “wants him gone.” He said he mentioned insurance money because Baker had told him about it.

Austin testified that Baker paid for his airline flight to Los Angeles and drove him the same night to a shopping center after getting a text message that Sementilli was going to send her husband out that night. He said he couldn’t go forward with the attack, but said the two men went the next day to the Sementilli family home to commit the killing after Baker received a text message.

“He said she’s going to the store. We have a small window,” said Austin, who told jurors that he learned then that the victim had a “kid” who might come back to the house.

The prosecution witness testified that Baker put him in the trunk of the rented Nissan and drove to an area where Baker gave him a knife and asked, “Are you with me?”

“Like a dummy, I said, ‘Yeah’ and followed him,” he said, noting that the two men ran up the hill to the victim’s home.

“He said the front door should be open, meaning unlocked. He told me, he said, ‘She’s gonna leave the door open,” Austin told jurors.

“… Did he tell you who she was?” the prosecutor asked.

“The defendant,” Austin responded, saying that the door was “indeed unlocked.”

He said Baker told him that the victim should be on the back patio and that the victim didn’t see him until Baker got close to him and tried to yell then.

“Baker covered his mouth and started stabbing him,” he said. “I covered his eyes and stabbed him once.”

He said he got into the passenger side of the victim’s Porsche at Baker’s request and saw Baker — whom he said had told him that it had to “look like a robbery” — returning with a pillowcase before the two men left in the vehicle. Austin said Baker eventually handed him items to throw out the car window and ordered him out of the Porsche before meeting up again with him on a main street.

Austin testified that Baker dumped the clothing they had been wearing in a trash bin and that he decided to return to Washington state a day early “because I couldn’t be there.” He said Baker stuck a roll of gold coins in his pocket that his friend said was valued at around $10,000 — an item that he said Baker told him had come from the victim’s safe.

“I told him, ‘I can’t believe you had me do that,’” he told jurors.

He said Baker responded, “It’s done. You’re still a good person,” and that Baker “couldn’t convince me that I was.”

Austin said he subsequently used a “burner” phone to communicate with Baker and began using an app to communicate with encrypted messages.

“He just said, ‘Don’t say anything … You’re going to be fine.’ I wasn’t OK,” Austin testified.

He said he heard once from Baker after he and Sementilli were arrested in 2017, telling jurors that his longtime friend told him not to say anything and not to mention “her” if anybody asked what happened.

He said Baker told him, “If anybody asks you, tell them I did it.”

Under cross-examination by defense attorney Leonard Levine, the prosecution witness acknowledged that he didn’t have any conversations himself with Sementilli about her husband’s killing and didn’t see any text messages from her to Baker.

He admitted that he was “a part” of the killing.

When asked why he didn’t say no to Baker about being involved in the crime, he said, “He was like family and he said that his girlfriend didn’t want him (the victim) around any more.”

He said he had only met Monica Sementilli at a gym and then returned with her and Baker to her home, where he was eventually left alone while the two retreated to a bedroom. He said Baker subsequently told him to remember the layout.

The prosecution witness testified that he didn’t give his full account to the jailhouse operative or Los Angeles police detectives when he initially spoke with them because he didn’t have an attorney with him at the time, and said he has “felt bad” ever since the killing.

“Did you know you were coming down to kill him?” Sementilli’s attorney asked.

He acknowledged that he did, but said he was “hoping it wasn’t going to happen.”

During the prosecution’s closing argument in Sementilli’s trial, Deputy District Attorney Beth Silverman told jurors that “it’s very obvious that the defendant, along with her lover, murdered Fabio Sementilli along with assistance from Christopher Austin,” and that the murder was “committed for financial gain as well as for other motivations — in other words, for their future together.”

She also urged jurors to find true the lying-in-wait special circumstance allegation, saying that the woman’s husband was “ambushed based on a secret plan or design that the defendant and her lover put into place,” and that Austin backed out of an effort to kill the victim a night earlier as he was picking up a take-out order at a restaurant.

“She’s the one who destroyed so many lives and their entire family,” said Silverman, who called the murder plot the ultimate act of “betrayal.”

Sementilli’s attorney countered hat his client was “guilty of a lot of things — stupidity, duplicity, lying, adultery” — but not murder.

“She was having an affair with someone who murdered her husband,” Levine said. “But she did not commit or orchestrate or conspire to commit the murder of her husband.”

“… She has suffered for her choices — and they were horrible,” the defense attorney said. “But she’s not guilty of first-degree murder, of destroying a family, putting her daughter in danger of being murdered when she could have controlled the whole thing.”

Levine described Baker as a “Svengali,” saying that Sementilli made the “biggest mistake of her life” in becoming involved in an extramarital affair with him.

“Nothing good came from Mr. Baker, but he’s gone for life,” Levine said of Baker’s plea and subsequent life prison sentence. “Now they want to complete the circle and send her away.”

Levine criticized Austin’s plea deal.

Sementilli has remained behind bars since her arrest in June 2017, when she and Baker were charged with murdering her husband. A conspiracy charge was subsequently added against the pair. The two were indicted just over two months later on the same charges.

Jurors heard a series of courthouse lockup recordings of conversations between Sementilli and Baker, including one in Van Nuys shortly after they were taken into custody. Baker can be heard repeatedly expressing his love for Sementilli and telling her that he’s “all in” and that he thinks they should get married.

“Just because we fell in love does not make us criminals,” Sementilli can be heard telling Baker at one point.

Austin has also remained behind bars since his arrest.