Ramon Joseph Rivas pleaded guilty to second-degree murder after Jessica Marie Tinoco was killed in front of her five children.
VENTURA, Calif. — A Simi Valley man was sentenced to 51 years to life in state prison Friday for murdering his girlfriend during a 2024 domestic dispute witnessed by her five children, the Ventura County District Attorney’s Office said.
Ramon Joseph Rivas, 36, received the sentence in the death of 34-year-old Jessica Marie Tinoco. He pleaded guilty May 20 to second-degree murder and admitted special allegations and aggravating factors, including using a deadly weapon, committing a crime involving great violence and having prior strike convictions. The Aug. 7 sentencing brought the criminal case to a major conclusion nearly two years after Tinoco was killed.
The killing happened Sept. 27, 2024, at a residence in Simi Valley, about 35 miles northwest of Los Angeles. Simi Valley police responded to a report of a stabbing and encountered Rivas as he came out of the home. Officers took him into custody and then entered the residence, where they found Tinoco near the front door with multiple injuries.
Tinoco was taken to Los Robles Hospital, where she was pronounced dead. Prosecutors said investigators recovered a bent steak knife from the living room. Authorities determined that several of Tinoco’s wounds were fatal. The district attorney’s office said the attack unfolded in front of her five children, who fled the home during the violence.
According to prosecutors, witnesses said Rivas and Tinoco had been involved in a domestic dispute before Rivas went into the kitchen, obtained a knife and attacked her. The district attorney’s office said Tinoco’s children were present as the attack began. Authorities have not publicly identified the children, and their names are being withheld because they are minors.
Senior Deputy District Attorney John Barrick, who prosecuted the case as a member of the office’s Major Crimes Homicide Unit, said Rivas’ decision to accept responsibility did not erase the harm caused to Tinoco and her family. Prosecutors had said when Rivas entered his plea that the fact the children witnessed their mother’s killing made the case especially devastating.
Rivas admitted several sentencing factors as part of his guilty plea. Court records cited by prosecutors included the use of a deadly weapon, Tinoco’s vulnerability, Rivas’ prior convictions and a history of violent conduct. The district attorney’s office also identified the case as a third-strike matter under California law, contributing to the lengthy prison sentence.
Members of Tinoco’s family addressed Rivas during sentencing, according to courtroom reports cited by Law&Crime. One of Tinoco’s daughters described the helplessness of watching the attack on her mother. Another told Rivas that he had lost the opportunity to experience the family life he once had.
Rivas also apologized during the hearing, according to the Ventura County Star account cited by Law&Crime. He described the killing as a decision that would remain with him and told Tinoco’s children he was sorry. Barrick said in the district attorney’s sentencing announcement that taking responsibility did not excuse the crime or its impact on the family.
The 51-years-to-life sentence was the maximum term prosecutors said Rivas faced when he pleaded guilty in May. He will serve the sentence in California state prison following his second-degree murder conviction and the sentencing enhancements he admitted.
Author note: Last updated August 8, 2026.