Miguel Diego Sandoval admitted four first-degree murders and other crimes in an attack prosecutors say followed the end of a relationship.

LOS ANGELES, Calif. — A 21-year-old man has pleaded guilty to murdering four young adults inside a Lancaster home, setting the house on fire and committing a series of related crimes in a 2024 attack that prosecutors say was carried out as revenge after the end of a romantic relationship. Miguel Diego Sandoval entered the pleas Aug. 13 and is scheduled to be sentenced Nov. 17 to life in prison without the possibility of parole, according to the Los Angeles County District Attorney’s Office.

The guilty pleas bring the criminal case to its sentencing stage nearly two years after deputies and firefighters rushed to a burning home on North Tabler Avenue in Lancaster in the early morning of Nov. 16, 2024. Prosecutors identified those killed as siblings Janvi Maquindang and Christine Aca-ac and their partners, Matthew Montebello and Edwin Garcia. A teenager who was inside the residence survived after calling 911 and was rescued from a locked bedroom. Prosecutors now say Sandoval had waited outside the home until its occupants went to bed before entering and opening fire.

Sandoval pleaded guilty to four counts of first-degree murder and admitted special-circumstance allegations of multiple murders and murder by means of lying in wait. He also pleaded guilty to attempted murder, first-degree residential burglary and arson of an inhabited structure or property, along with three felony counts of animal cruelty and two felony counts of child abuse under circumstances likely to cause great bodily injury or death. The District Attorney’s Office said the plea will result in life imprisonment without parole. A separate court report said the expected sentence consists of four consecutive life terms without the possibility of parole.

The prosecution’s latest account provides a clearer description of what happened before the killings than authorities released during the first days of the investigation. The District Attorney’s Office said Sandoval remained outside the North Tabler Avenue residence until the people inside had gone to bed. He then entered and fatally shot the four victims. The office said Sandoval acted in revenge after the end of a relationship with the brother of Aca-ac and Maquindang. That alleged motive had not been publicly established when homicide investigators announced Sandoval’s arrest in November 2024, when authorities described the shooting as an isolated incident and said the motive remained under investigation.

After the shootings, prosecutors said, Sandoval set the house on fire and fled. The fire changed the emergency from a shooting scene into a rescue operation inside a burning residence. A 16-year-old victim who remained inside called 911 and stayed in a locked bedroom until Los Angeles County sheriff’s deputies reached the home and rescued the teenager. Earlier reports said three of the four adults were pronounced dead at the scene and another victim was taken to a hospital in critical condition before later dying. The guilty pleas also cover an attempted-murder count and child-abuse counts associated with people who survived the attack, though prosecutors’ public plea announcement did not provide a detailed narrative for each of those charges.

Three dogs also died in the fire, according to court reporting and the charges admitted by Sandoval. Prosecutors included one felony animal-cruelty count for each dog. The arson charge concerned an inhabited structure or property, while the burglary count concerned Sandoval’s entry into the residence before the shootings. Taken together, the pleas resolve a case that originally centered on four murder charges but ultimately included crimes reflecting the other people and animals endangered inside the home. Authorities have avoided releasing a detailed minute-by-minute account beyond the facts needed to describe the prosecution and the plea.

Los Angeles County District Attorney Nathan J. Hochman described the killings as a calculated act carried out after the breakup. He said the victims’ families were left with a loss that could not be repaired and said the plea ensures Sandoval will spend his life in prison. The plea announcement marks a change from the legal posture of the case in late 2024, when Sandoval was a defendant facing allegations that had not been proved. His guilty pleas now establish criminal responsibility for the offenses he admitted, while the formal imposition of sentence remains scheduled for November.

The case began publicly as a homicide and fire investigation. Deputies responded to the 44500 block of North Tabler Avenue at about 1:27 a.m. on Nov. 16, 2024, after the emergency call. Firefighters were dispatched as the single-story residence burned. Investigators later arrested Sandoval, who was 19 at the time, and the District Attorney’s Office announced murder, burglary and arson charges on Nov. 26. The original charging announcement also alleged that the killings involved lying in wait and multiple murders and that a handgun was used. At that stage, prosecutors said the fire was set after the shootings to conceal the crimes. Sandoval was held without bail while the prosecution moved forward.

The victims’ relatives later described the four as two young couples who shared the Lancaster home. Garcia and Aca-ac were engaged, while Maquindang and Montebello were partners, according to family interviews given after the killings. Garcia’s relatives remembered him as loving and attentive to other people. Montebello’s mother described her son as kind, caring, intelligent and creative and recalled having dinner with him shortly before he died. Family members said the household largely kept to itself, while neighbors described the residents as polite and familiar faces in the small cul-de-sac. The families created fundraisers after the deaths to help cover funeral and related expenses.

Those family accounts also placed the losses within a larger household. Aca-ac was described by relatives as a guardian for younger siblings, making the attack not only the killing of four adults but also a sudden disruption of a family home. The teenager’s 911 call became one of the central facts in early reports because it alerted authorities while the residence was burning. The teenager was not physically injured in the attack, according to authorities. Prosecutors have not publicly released a detailed account of what the surviving young people saw or heard, and their identities have not been broadly published in official accounts.

Some public records and news reports issued at different stages of the case have listed inconsistent ages for several victims. The District Attorney’s August 2026 plea announcement identified Maquindang as 21, Aca-ac as 25, Garcia as 24 and Montebello as 21. Earlier official and news accounts gave different ages for some of them. The differences do not alter the identities of the four people killed or the charges Sandoval admitted, but the latest District Attorney’s Office announcement is the controlling public account for the plea and sentencing stage.

Sandoval’s case is being prosecuted by Deputy District Attorney Alexander Bott of the Major Crimes Division and was investigated by the Los Angeles County Sheriff’s Department. His sentencing is scheduled for Nov. 17 in Department 105 of the Foltz Criminal Justice Center in Los Angeles. With the guilty pleas entered, the principal remaining court step is the formal sentence. Prosecutors have said that sentence will be life in prison without the possibility of parole.

Author note: Last updated September 28, 2026.