Ramon Joseph Rivas pleaded guilty to killing Jessica Marie Tinoco during a 2024 domestic dispute witnessed by her children.

VENTURA, Calif. — A Simi Valley man has been sentenced to 51 years to life in state prison for the 2024 murder of his girlfriend, Jessica Marie Tinoco, bringing the criminal case to a close nearly two years after the mother of five was fatally attacked inside the home she shared with him.

Ramon Joseph Rivas, 36, received the sentence Aug. 7 after pleading guilty May 20 to second-degree murder, according to the Ventura County District Attorney’s Office. Rivas also admitted a series of special allegations and aggravating factors that included using a deadly weapon, committing a crime involving great violence, targeting a particularly vulnerable victim and having prior strike convictions. Prosecutors said he also admitted allegations tied to a prior serious or violent felony, a prior prison term and earlier convictions. The sentence imposed by the court was the maximum term prosecutors said Rivas faced when his guilty plea was announced in May.

The sentencing put the focus back on what Tinoco’s children experienced on Sept. 27, 2024. Prosecutors said the killing occurred in front of her five children during a domestic dispute at the Simi Valley residence. Earlier police-based reporting said two children were present during the attack and that one called 911. The District Attorney’s Office later described all five children as having been there as the violence unfolded and said they fled the residence. The differing descriptions appear to concern how many children directly witnessed the attack, but authorities have consistently said Tinoco’s children were inside or immediately involved in the emergency and that at least one child summoned police.

At the sentencing hearing, members of Tinoco’s family described the damage left by the killing. Her daughter Kimberly Gutierrez told the court about trying to intervene and begging Rivas to stop, according to courtroom reporting by the Ventura County Star. Another daughter, Mariah Gutierrez, described getting her siblings out of the home and calling 911. Their statements placed the children’s actions at the center of the hearing: They were not only witnesses to the attack but also the people who had to react as their mother was being killed. Tinoco’s mother also addressed the court and spoke about the loss of her daughter and the consequences for the family.

Rivas addressed Tinoco’s relatives during the proceeding and expressed shame and regret for what he had done. Law&Crime, citing the Ventura County Star, reported that he apologized directly to two of Tinoco’s children who attended the hearing and said, “I’m so, so sorry.” Senior Deputy District Attorney John Barrick, who prosecuted the case as part of the office’s Major Crimes Homicide Unit, said the guilty plea and acceptance of responsibility did not erase the damage caused by the killing. The prosecution had made a similar point when Rivas entered his plea, emphasizing that the children had been forced to experience the violence against their mother.

The attack happened the evening of Sept. 27, 2024. According to prosecutors, Simi Valley police responded to a report of a stabbing at the residence. Officers arriving at the home encountered Rivas coming outside shirtless with blood on his upper torso and took him into custody. Inside, officers found the 34-year-old Tinoco near the front door with multiple wounds. Police also recovered a bent, bloodstained steak knife from the living room floor and found blood elsewhere inside the residence. Tinoco was taken to Los Robles Hospital, where she was pronounced dead.

Witnesses told investigators that the violence began during a domestic dispute, according to the District Attorney’s Office. Prosecutors said Rivas went into the kitchen, obtained a knife and attacked Tinoco. Authorities said she suffered multiple wounds and that four were determined to be fatal. The children fled as the attack unfolded. The official account released at sentencing did not provide a detailed description of what prompted the dispute, and prosecutors did not identify a broader motive beyond the domestic confrontation. The public record therefore establishes the sequence of the attack without explaining what Rivas believed or intended before the dispute escalated into deadly violence.

The criminal case changed significantly between the initial filing and the eventual guilty plea. When the District Attorney’s Office announced charges in October 2024, Rivas was accused of murder, child endangerment and strike-related allegations. Prosecutors at that stage described several of Tinoco’s children as having been present. He was held without bail as the case proceeded in Ventura County Superior Court. By the time of the May 2026 resolution, court reporting said the case included four child-endangerment counts. Those remaining counts were to be dismissed as part of the plea arrangement, while Rivas admitted second-degree murder and multiple sentencing allegations. The plea eliminated the need for a murder trial and moved the case directly toward punishment.

The admitted allegations were important to the length of the sentence. The District Attorney’s Office listed a deadly-weapon allegation, a third-strike allegation, a prior serious or violent felony and a serious-felony prior. Prosecutors also listed aggravating factors concerning the violence of the crime, Tinoco’s vulnerability, Rivas’ prior convictions, a prior prison term and a history of violent conduct. The office did not provide a paragraph-by-paragraph calculation in its sentencing announcement showing how each component added to the final term, so the precise mathematical breakdown should not be inferred from the public release. What is clear from the record is that Rivas pleaded guilty knowing prosecutors said he faced as much as 51 years to life, and the court ultimately imposed that term.

The guilty plea in May marked a decisive point in a case that had remained pending since Rivas’ arrest on the night of the killing. In announcing the plea, Barrick said the presence of Tinoco’s children made the crime especially consequential for her family. Prosecutors said no prison term could undo what they had witnessed. The later sentencing announcement was more concise but carried the same message: Rivas’ decision to accept criminal responsibility was relevant to the case’s resolution, but it did not diminish the seriousness of the murder or its effect on Tinoco’s relatives.

Tinoco was remembered in local reporting as a mother whose death left five children without her. Coverage after the killing documented grief among relatives, friends and members of the surrounding community. Those details became especially significant at sentencing because the hearing gave family members a formal opportunity to tell the court how the murder had affected them. Their accounts shifted attention away from the mechanics of the plea and enhancements and toward the continuing consequences of a crime that unfolded inside a family home.

The Aug. 7 sentencing completes the principal criminal proceeding against Rivas in Ventura County Superior Court. He now faces a 51-years-to-life state-prison term on the second-degree murder conviction and the allegations he admitted. The public sentencing materials do not identify another pending hearing in the murder case. For Tinoco’s family, the legal process has reached its punishment phase, while the statements delivered in court made clear that the effects of her death extend far beyond the judgment entered against the man who killed her.

Author note: Last updated September 21, 2026.