A Sonoma County judge has denied mental health diversion to a former Cal Fire engineer charged with setting five fires near Geyserville, Healdsburg and Windsor in 2024, ruling that the risk of letting him go through treatment instead of prosecution was simply too high. Robert Matthew Hernandez, who remains in custody without bail, is now headed toward a jury trial on five felony arson counts.
Judge Karlene Navarro issued the written ruling, according to The Press Democrat, after hearing diversion arguments on Aug. 14, 2026. Had diversion been granted, it could have led to the dismissal of all charges following two years of court-monitored mental health treatment instead of incarceration.
Hernandez applied for mental health diversion in November 2025. Public defenders said he had been diagnosed with PTSD, ADHD, stimulant-use disorder and alcohol-use disorder, with the stimulant and alcohol disorders described as severe. Attorney Jessyca Hoagland wrote that Hernandez had remained sober since his arrest, was committed to treatment and posed no threat to public safety.
Prosecutors Pointed to a Pattern of Relapse
Navarro ultimately sided with prosecutors, who argued Hernandez posed a risk of committing what the law classifies as a super strike — a category that includes murder, voluntary manslaughter, major sex crimes and use of a weapon of mass destruction — if he were treated in the community rather than prosecuted. Mental health diversion, available to certain petitioners since 2018, excludes anyone likely to commit such offenses and generally requires a treatable mental disorder diagnosed within five years of the offense and linked to it.
In her ruling, Navarro wrote: “If Mr. Hernandez cannot get his substance use disorder under control — which on this record appears doubtful — his history shows that he will, in fact, not participate meaningfully and will abandon treatment.” She also wrote that “at the time of the instant charges, Mr. Hernandez was using alcohol and methamphetamine on a daily basis including while he was driving from place to place setting fires,” and expressed concern that he might not commit to treatment and could remain a threat to the community.
According to Navarro's ruling, Hernandez began drinking alcohol and smoking marijuana around age 10, snorted cocaine in high school, and was hospitalized for advanced pancreatitis caused by alcoholism in 2016, when he was 29. He continued drinking after his hospital discharge and until his arrest later that year in a fatal San Bernardino collision, the ruling states. He also told a therapist he consumed alcohol and methamphetamine while employed by Cal Fire, and reported having no memory of setting the fires because he was blacked out, per the same ruling. Prosecutors argued that his alleged unawareness while starting the fires did not reduce the danger those fires posed to the community.
From Prison Fire Crews to a Cal Fire Career
Hernandez was sentenced to six years for gross vehicular manslaughter while intoxicated, according to the Los Angeles Times, and participated in the state's inmate firefighter program while serving that sentence. He later had the manslaughter conviction expunged. In 2019, while on parole, he completed training at the Ventura Training Center, which is designed to help formerly incarcerated firefighters transition into careers with public agencies; he was released from parole in November 2020.
He continued abusing drugs and alcohol even after his conviction and sentence for vehicular manslaughter, per Navarro's ruling, and was later identified by investigators as being at high risk of relapse without appropriate treatment. Cal Fire has not publicly commented on the case or confirmed Hernandez's current employment status, the report notes.
GPS Tracker Led Investigators to the Fires
The five fires — the Alexander Fire off Soda Rock Road north of Healdsburg on Aug. 15, 2024; the Windsor River Road Fire east of Windsor on Sept. 8; the Geysers Fire north of Cloverdale on Sept. 12; and the Geyser and Kinley fires near Healdsburg on Sept. 14 — broke out while Sonoma County was under a state of emergency amid dry grass and drought conditions. Investigators first linked Hernandez to the Alexander Fire by connecting him to the only active cellphone in the area at the time, then installed a GPS tracker on his Jeep Compass on Aug. 29, 2024, while it was parked outside a Target store at Santa Rosa's Coddingtown Mall.
Over the following two weeks, investigators traced Hernandez's movements and said GPS data placed him at the scenes of the remaining fires, where he lingered for a few minutes before driving away each time. Cal Fire personnel stationed nearby quickly extinguished the fires before they could spread, limiting the damage. Hernandez was arrested Sept. 20, 2024, at the Howard Forest Fire Station in Willits, and prosecutors charged him shortly after with five counts of arson. A search of his vehicle, per court records, turned up multiple torch lighters, a blow torch, three twisted or rolled-up pieces of paper and a jacket with burn marks. Judge Troye Shaffer later found enough evidence to send the case to trial.
A New State Law Could Reshape Future Cases
Hernandez's case unfolded as California moved to tighten the rules around mental health diversion statewide. Gov. Gavin Newsom signed Assembly Bill 46 into law in June 2026, and the measure takes effect Jan. 1, 2027. The law raises the standards for diversion and gives judges more discretion, requiring courts to consider a defendant's entire criminal history and to find that a defendant will not pose a substantial and undue risk to another person's physical safety if treated in the community, according to CBS Sacramento.
The law also lets courts weigh whether a proposed treatment plan is clinically appropriate for the mental health condition tied to the offense, per the Riverside County District Attorney's office, while reaffirming that judges can still deny diversion outright when public-safety concerns outweigh the benefits of treatment. Separately, the California Courts Newsroom has noted a Court of Appeal holding indicating that a defendant's history of relapsing after residential drug-and-alcohol treatment may be considered relevant in a diversion analysis.
Hernandez is expected back in court in November 2026 as his case moves toward a jury trial. He remains held at the Sonoma County jail without bail, with no resolution yet to the five arson counts against him.
