The verdict follows a 2024 attack at Salinas Valley State Prison that prosecutors said involved 42 stab wounds.
SOLEDAD, Calif. — A state prisoner who had arrived months earlier for trying to murder his father has been convicted of killing a fellow inmate in a Salinas Valley prison yard attack, officials said.
The case centered on a brief and violent episode inside Salinas Valley State Prison on Aug. 19, 2024. State officials said the attack began at 10:31 a.m. on a recreation yard. The victim, Michael R. Spengler, 38, was attacked with an inmate-made weapon and was pronounced dead at 11:08 a.m. Prosecutors later said he had been stabbed 42 times and died from injuries that caused extensive hemorrhaging.
Miguel Angel Espino, 33, was convicted April 23, 2026, of willful, deliberate and premeditated murder. Monterey County District Attorney Jeannine M. Pacioni announced the verdict four days later. The case was tried before Superior Court Judge Stephanie E. Hulsey. Prosecutors said the jury also found that the killing involved a high degree of cruelty, viciousness and callousness. That finding came on top of Espino’s existing record, which included three Riverside County convictions that the court found qualify as strikes under California’s Three Strikes Law.
Corrections officials said staff quickly stopped the prison yard assault, called for medical help and contacted 911. No staff members or other incarcerated people were injured. Officers recovered one inmate-made weapon at the scene, and Espino was placed in restricted housing while the prison’s Investigative Services Unit and the Monterey County District Attorney’s Office investigated. The Office of the Inspector General was notified, as is standard in serious prison cases, and the Monterey County Coroner was assigned to determine the official cause of death.
The victim was not new to the criminal justice system. Spengler had been received into state prison from Los Angeles County on Aug. 9, 2022, to serve life without the possibility of parole. His sentence came from convictions for first-degree murder and second-degree murder in the deaths of Michael Meza, 32, of Pomona, and Marcus Nieto, 26, of Azusa. The killings happened during the winter of 2013. At sentencing in July 2022, Los Angeles County Superior Court Judge Henry J. Hall said the murders appeared to be surprise ambushes of Spengler’s own friends.
Hall said then that the killings appeared largely senseless and that Spengler should never be released from prison. A prosecutor in that case said the motive for the two murders was unknown. Spengler had confessed to the killings to a jailhouse informant, according to earlier reports of the Los Angeles case. By the time of the 2024 prison yard attack, Spengler had been in state custody for about two years. Prison officials did not release a suspected motive in the attack that killed him.
Espino’s path to Salinas Valley State Prison began in Riverside County. He was received into state custody Feb. 8, 2024, after convictions for attempted first-degree murder, inflicting great bodily injury, personal use of a dangerous or deadly weapon, aggravated mayhem and arson of an inhabited structure. The convictions arose from an Aug. 7, 2018, attack at a mobile home in Desert Hot Springs. Prosecutors said Espino and his father, Arturo Espino Sr., had a long record of arguments and physical confrontations before the assault.
According to trial filings in the Riverside County case, the father and son were alone in the mobile home when another argument turned violent. Prosecutors said Miguel Espino beat his father about the head with a hammer and a rock, causing major trauma. After Arturo Espino fell unconscious, prosecutors said, his son gathered clothing in the hallway, used flammable liquids and set the pile on fire. He then fled the home. The mobile home was in a park on Palm Drive, where neighbors had seen earlier conflicts involving the family.
Neighbors became central to the father’s survival. They saw smoke, rushed into the burning home, fought the fire with an extinguisher and called 911. They pulled Arturo Espino outside before county fire personnel arrived and fully put out the smoldering blaze. An arson investigator quickly determined that the fire had been set on purpose. Arturo Espino was taken to Desert Regional Medical Center in Palm Springs, where doctors first feared he might not live. He stayed comatose for days before he regained consciousness.
Investigators built the Riverside County case through witness statements, family history and recorded calls. Desert Hot Springs police and Cal Fire arson investigators identified Miguel Espino as the prime suspect after speaking with neighbors and Espino’s mother. Court filings said his mother had moved out of the mobile home park and had obtained a restraining order against him because she feared for her life and property. Espino was arrested the day after the attack. He denied hurting his father, but prosecutors said his jail calls with his mother showed otherwise.
In one recorded conversation cited in court filings, Espino said his father tried to assault him with a knife and that he responded with a rock and hammer. Prosecutors also said he told investigators another person was inside the home and started the fire. The Riverside County case went to trial in 2023 at the Banning Justice Center. Espino later entered state prison with a seven-years-to-life sentence. Within months, the prison yard homicide at Salinas Valley created a second life-term case against him.
The new conviction carries a far longer possible sentence than the term Espino was already serving. Prosecutors said he faces 75 years to life, consecutive to the seven-years-to-life sentence from Riverside County. The prior attempted murder, mayhem and arson convictions were found true by the court as strike offenses. That means the new sentence would be stacked on top of his existing punishment rather than replacing it. Prosecutors did not list a public sentencing date in the verdict announcement.
Salinas Valley State Prison opened in 1996 and holds more than 3,300 incarcerated people across several security levels. It also has about 1,500 employees and runs academic and vocational programs. The killing placed prison staff, local prosecutors and state oversight officials into the same case file, starting with emergency response on the yard and ending, for now, with a Monterey County jury’s murder verdict.
No sentencing date was listed in the announcement. When the court returns to the case, the focus will shift from what happened on the yard to how the new life term is added to Espino’s existing sentence.
Author note: Last updated May 21, 2026.