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Monica Sementilli and Robert Baker jail love affair reveals evidence of murder conspiracy, say prosecutors

The Monica Sementilli Affair
The Monica Sementilli Affair 40:56

When Monica Sementilli and Robert Baker were arrested and accused of a murder conspiracy to kill Monica's husband, Fabio Sementilli, 49, their love affair continued in jail according to documents revealed in a "48 Hours" investigation of the case. Prosecutors allege their ongoing love affair behind bars, including recordings made during police sting operations, represent further evidence of a committed murder conspiracy between the lovebirds.

"It kind of hurts to not be touched or f***** or licked or loved by you," Monica, now 52, writes in one four-page letter to her codefendant. Baker, now 61, is blunt, recorded addressing Sementilli in lockup months after their arrest, "I love you baby. I really do."

Monica Sementilli and Robert Baker mugshots
Monica Sementilli and Robert Baker LAPD

On June 14, 2017, Baker and Monica were arrested and ultimately indicted for Fabio's murder and conspiracy to commit murder. Baker pleaded no contest in July 2023, accepting a life sentence without parole. Monica will stand trial alone in April; she has pleaded not guilty. Their case is profiled by "48 Hours" contributor Michelle Miller in "The Monica Sementilli Affair" now streaming on Paramount+.

On the day of their arrest, according to a recording released by police, Monica tells a cellmate how much Baker means to her: "He's not just my lover, he's my confidant, he's my everything."

Police engaged in an elaborate series of sting operations to continue to investigate the alleged conspiracy between the defendants even while they were held in custody, "48 Hours" has discovered. Police alternately used standard and creative means to intercept or record the defendants' interactions and statements, all of which is being offered as evidence of conspiracy in Monica's upcoming trial.

For instance, "48 Hours" has confirmed that the cellmate to whom Monica spoke when she was first detained was an undercover police officer posing as an inmate to catch Monica speaking candidly on surreptitious recordings. Police call these types of jailhouse setups where officers pose as inmates inside jail Perkins Operations, referring to the case law which guides how these in-jail, sting operations are conducted.

In the course of our investigation, "48 Hours" has learned that police went to even greater lengths than using undercover officers inside cells to ensnare Monica and Baker. As the two defendants were brought to courtrooms for their initial pre-trial hearings, detectives made arrangements for them to be held in adjoining cells prior to the hearings.

Monica Sementilli and Robert Baker in court.
Monica Sementilli, left, and Robert Baker during a court appearance. CBS News

Waiting in nearby cells to be brought into the courtroom, Monica and Baker had an opportunity to speak directly to each other. On six different occasions, first at the Van Nuys Courthouse and then at the downtown Los Angeles criminal courthouse, interactions between Monica and Baker were recorded. 

Beyond the sting operations, detectives also intercepted jail letters, referred to by inmates as "kites," and listened to recorded jail phone calls to establish facts about the enduring love affair between Monica and Baker.

"48 Hours" has obtained copies of three different jail love letters written from Monica to Baker which we have learned police intercepted while Monica intended to pass them to Baker in courthouse holding cells. "48 Hours" has learned that the detectives discovered the letters in holding cells while Monica and Baker attended the hearings. The detectives hastily made copies before carefully returning them for the inmates to retrieve after the hearings so that the defendants were unaware the love letters had been intercepted and copied.

Meanwhile, Monica's defense has repeatedly argued, "the sexual and romantic details of their affair were simply irrelevant to the question whether they conspired to murder Fabio Sementilli."

According to prosecutors the information gleaned from these operations establishes that the ongoing jailhouse love affair is further evidence of the murder conspiracy between the accused.

"In essence, the defendants have promised one another that neither will cooperate with law enforcement or testify against the other to save themselves. Rather, they have promised one another that neither will cooperate with law enforcement or testify against the other to save themselves," wrote Deputy District Attorney Beth Silverman.

The unusual situation where the two inmates could speak to each other while detained was designed by law enforcement purposely to record conversations between the unwitting defendants.

Monica Sementilli and Robert Baker used secret code to express love and commitment inside jail, prosecutors cite as evidence of murder conspiracy

According to a 2021 motion filed by the prosecutor, the recordings and intercepted love letters are evidence of an ongoing "secrecy pact" between the accused.

"The defendants often communicated with one another using cryptic language, phrases and codes created in order to secretly communicate without law enforcement's knowledge," including, "the phrases, 'OMM,' '9pm,' 'LOML,' and '100,'" according to a prosecution filing.

Prosecutors allege these coded phrases establish the defendants' love and commitment not only to each other, but also the "conspiracy" and "secrecy pact" between them. "OMM," they allege, means "On My Mind," while they say "9pm" is a reference to a secretive plan to break jail rules and set timing for a phone call where a third party will connect the two to speak directly. The prosecutors contend "LOML" is an "acronym meaning 'Love of My Life' and '100' indicates their 100% commitment to one another."

According to prosecutors, another significant phrase is the one written at the end of one of Monica's love letters, "R or D," an alleged abbreviation for the phrase "Ride or Die."

Robert Baker Ride or Die cellphone mage
A drawing found on Robert Baker's cellphone entitled 'Ride or Die.'"  Prosecutors allege it represents a commitment between Baker and his lover, co-defendant Monica Sementilli, to "remain loyal to one another, and never 'talk' to law enforcement about their conspiracy; in their words, they would "'Ride or Die' for one another."   Los Angeles County Superior Court

Detectives found a drawing "depicting a couple embracing one another wearing only underwear and ski masks while holding guns" in Baker's cellphone "entitled 'Ride or Die.'" There is a statement above the drawing, "A relationship where you both love, protect and spoil each other is the best."

"The phrase 'Ride or Die' was frequently used between the defendants as an expression of their commitment to one another and their secrecy pact. On several occasions defendants expressed that they would remain loyal to one another, and never 'talk' to law enforcement about their conspiracy; in their words, they would 'Ride or Die' for one another," the 2021 filing asserts.

Robert Baker and Monica Sementilli allegedly play sex games during recorded jailhouse encounters arranged and recorded by police

The two lovers took advantage of six rendezvous engineered by detectives, according to motions filed in court. Monica and Baker were recorded "talking to one another and engaging in masturbation and other sex games," wrote the prosecutor. The judge has ruled the alleged sex games portions of these recordings will not be admissible. Nevertheless, these encounters purportedly reveal the passionate nature of their continuing relationship in jail.

Baker confirmed the sex games during an exclusive jailhouse interview with "48 Hours" on March 2. That's what happens when you are stuck in here, he said, gesturing to the jail side of the glass from where he talked to a reporter over a phone.

Once those encounters stopped, the jailhouse co-defendants and lovebirds found ways to break the rules and remain in contact, according to prosecutors. In that 2021 filing, prosecutors said "over the course of the last four years, the defendants made hundreds of calls through third parties … This allows them to speak to one another."      

These phone recordings have been shared with the defense as discovery but have not been made public.

In excerpts reviewed by "48 Hours" from two of the six recorded encounters, there is talk of marriage, and in her letters, Monica consistently refers to herself as "Mrs. Baker," "Monica Baker" and "your wifey." "MB" is a code prosecutors allege is an abbreviation of Monica Baker.

"The defendants have continued to refer to one another as husband and wife while in custody for murdering Sementilli's legitimate husband," wrote the prosecutor, who cites this as dedication, not only to each other, but also to their murder conspiracy.

Before the grand jury, prosecutor Silverman argued that the lovers' commitment motivated the conspiracy, saying they were "plotting to kill [Fabio] in order to collect his substantial life insurance monies and be able to live hopefully happily ever after." 

Monica's attorneys have repeatedly challenged the evidence of a love affair as irrelevant to proving evidence of a murder conspiracy. There is no doubt, however, that Monica and Baker's  commitment to their affair endured at least during the early months in jail, even for years according to the prosecutor.

"We will get married … You are the perfect wife for me. Beyond belief. My mind is like, I'm delirious," Baker says to Monica in a lockup recording.

Monica Sementilli letter
A letter from Monica Sementilli to Robert Baker signed, "Love, your wifey ... Monica Baker 'til death. R or D" Los Angeles County Superior Court

Similarly, she gushes to her lover as she ends a three-page-long letter, or "kite," intercepted on Aug. 6, 2017, with "Love your wifey… Monica Baker 'til death. R or D"  

In jail sting, Robert Baker mentions Monica Sementilli facing "difficulty" of being "disowned" for loving and wanting to marry him

"48 Hours" has identified one comment relating to this alleged jailhouse marriage talk that may indicate a separate issue at play in the murder conspiracy allegations.

During the grand jury hearings, prosecutor Silverman argued divorce was not an option for Monica, so the couple instead turned to murder.

"She's from an Italian family, which means Catholic. They don't believe in divorce, her family won't, it won't be easy for them to take it … So again this provides a motive," said Silverman.

Monica's defense attorneys have challenged this testimony as flimsy and misinterpreted, insisting the prosecutor has not established that divorce troubled Monica.

However, in one of the recorded conversations between Baker and Monica on Aug. 31, 2017, which police refer to as "lockup overhears," Baker seems to make a stunning admission regarding Monica while they discuss their desire to get married.

"So, when you gonna tell them … when you … when you gonna tell them … how we gonna tell 'em we're gonna get married? How we gonna do this? Then you'll really be officially disowned for loving somebody," Baker says in a seeming reference to Monica getting disowned for their relationship. Monica responds, "I don't know … I think we may need to wait … until the trial, and see what happens with that."

Baker then says, "I'm not the one that has the, difficulty you do."

The transcript made public in the prosecutor's motion is only an incomplete excerpt of the conversation. Nevertheless, this portion of the jailhouse exchange recorded by the Los Angeles Police Department seems to establish that Monica being "disowned" over her love for Baker may have been an issue for the lovers. Furthermore, Baker seems to confirm it as a "difficulty" for Monica. It is a tantalizing piece of a conversation, raising a significant issue that will almost certainly come into play during her trial.

Monica's defense attorneys "are not commenting on any evidence until it is presented at trial," said veteran L.A. criminal defense attorney Leonard Levine.

Monica Sementilli and Robert Baker in Las Vegas in March 2017 - months after Fabio Sementilli's stabbing death. Los Angeles County Superior Court

Although it is unclear if the two defendants remain in contact today, after six years of incarceration, evidence appears to demonstrate the stunning revelation they remained dedicated to a relationship in the months after their arrest, perhaps extending for years. These love letters, sex games and promises seem to have continued even after Monica learned that evidence implicated Baker as her husband's killer.

In an exclusive jailhouse interview with "48 Hours," Baker claimed that now the two are prevented from contacting each other.  He said, the last time they spoke, in a random encounter passing each other in lockup, she cursed him as a murderer. He did not indicate when this exchange occurred. 

Calling Baker a murderer would represent a significant turn in Monica's attitude, as evidenced through August 2017 in the jail letters and recordings. In his interview with "48 Hours," Baker claimed that Monica took no part in a murder conspiracy and that he acted without her knowledge.

Prosecutors dismiss the idea that Monica was not involved, detailing 56 overt acts which they argue constitute the conspiracy between the two lovers to murder the celebrity hairstylist turned beauty industry executive.

Monica's defense attorneys intend to call Baker as a witness during Monica's trial.

"We are confident that Robert Baker's guilty 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," said Levine after Baker's sentencing.

Whether or not Monica Sementilli's love affair with killer Robert Baker constitutes evidence of a criminal conspiracy or simply passionate infidelity will be at the heart of Fabio's wife's trial for his murder. Prosecutors plan to enter details of that love affair dating as far back as one year before the crime, continuing after Fabio's murder, and as revealed by "48 Hours"' investigation, even while the two were locked up awaiting trial.

Greg Fisher is a development producer for "48 Hours." He has covered the Fabio Sementilli case since 2017.

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