Cal-OSHA<\/a>, the agency charged with investigating workplace safety and finding out what happened here, was one of the agencies on the site. Sources familiar with the investigation said Cal-OSHA\u2019s team was repeatedly prevented from doing its job by Cal Fire, another state agency.<\/p>\n According to multiple officials and emails, a unit of four arson and bomb investigators from Cal Fire\u2019s Office of the State Fire Marshal<\/a> \u2014 which regulates fireworks in California \u2014 told witnesses at times not to talk to Cal-OSHA investigators and did not provide documents vital to Cal-OSHA\u2019s investigation.<\/p>\n Parallel worker safety and criminal investigations are fairly common. On the federal level numerous agreements<\/a> spell out cooperation between the U.S. Justice Dept and federal OSHA when they have parallel investigations. But in California, tensions over the Esparto investigation simmered for months and resonate today.<\/p>\n The schism was partially resolved through high-level meetings between the agencies and a memorandum of understanding forged last August. But dueling investigations, with one allegedly impeding the other, resulted in a delay in Cal-OSHA\u2019s work, sources said. The agency is on the clock with its investigations, mandated by the state to complete accident investigations within six months, and, sources said, delays affect its ability to assess fines and determine criminality, and may have harmed families ability to receive restitution.<\/p>\n A document marked \u201cconfidential,\u201d addressed \u201cthe investigation of and potential enforcement actions surrounding the explosion at the fireworks warehouse in Esparto, California, on July 1, 2025,\u201d and prescribed a process for both agencies to share information with each other.<\/p>\n Cal Fire spokesperson Emily Weinzheimer, asked about the alleged blocking of Cal-OSHA investigators, said Cal Fire\u2019s actions were part of a process.<\/p>\n \u201cCAL FIRE investigators were conducting a criminal investigation and initially wanted to ensure all interviews were completed prior to other investigators (OSHA) conducting interviews,\u201d she said in an email. \u201cTo ensure both agencies achieved their statutory responsibilities, Chief (Daniel) Berlant reached out to Deputy Director Adam Romero at Cal\/OSHA to ensure both agencies were aware of one another\u2019s processes and ensured cooperation among both agencies.\u201d<\/p>\n The criminal investigation resulted in eight people indicted<\/a> by the Yolo County Grand Jury, including former Yolo County sheriff\u2019s lieutenant Samuel Machado. Five face murder charges.<\/p>\n Still, according to state officials, who did not wish to be identified because they were not authorized to speak publicly about the case, some of the consequences for Cal-OSHA were:<\/p>\n It was not able to speak to multiple witnesses for months, missing a key window when recollection is clearest.Cal Fire did not share information about its interviews, keeping Cal-OSHA in dark about some individuals now facing serious criminal chargesOfficials also said that Cal-OSHA was unable to determine within the statute whether Black Star Fireworks, whose owner Craig Cutright was charged with making false statements and possession of illegal explosives, had employees despite some evidence that he did. Cal-OSHA issued no citations to Blackstar.Cal-OSHA\u2019s Bureau of Investigations, which recommends labor code-based criminal prosecutions, has been delayed in its investigation by Cal Fire, too, sources said. They noted that impeding the BOI work can hurt families \u2014 resulting prosecutions from its work can result in seven-figure restitution.<\/p>\n Attorney Mark Berry, who represents the family of Angel Boller, an 18-year-old worker who died, witnessed the tension.<\/p>\n \u201cI was troubled by it,\u201d he said. \u201cThe Vollers were troubled by it.\u201d<\/p>\n Interview allegedly blocked<\/p>\n Berry said on July 21, two Cal-OSHA investigators \u2014 Joey Crawford and Martin Lapp \u2014 drove to Lodi to interview Julian Voller, Angel\u2019s brother and a two-year employee with Devastating Pyrotechnics, the fireworks company operating the warehouse.<\/p>\n Crawford and Lapp wanted to speak to Voller because he was one of the only surviving workers<\/a>. Julian had escaped only by chance, having taken his daughter to Great America that day for her birthday. When word of some kind of explosion had reached him. Julian rushed to Esparto, dialing Angel\u2019s cell phone the whole way. It went straight to voicemail, Berry said.<\/p>\n Voller was close with his younger brother Angel, a star baseball player who had just graduated from high school. The two had spoken on the phone shortly before the blast.<\/p>\n When the Cal-OSHA investigators arrived in Lodi, Voller was a no-show.<\/p>\n Berry later apologized by email to Crocker, Cal-OSHA\u2019s Sacramento District Manager, explaining that an arson and bomb investigator for Cal Fire, Gershom Slonim, had told Voller not to grant the interview.<\/p>\n \u201cMr. Crocker: I am sorry you unnecessarily had to drive to Lodi,\u201d Berry wrote. \u201cI was requested not to produce Julian for our July 21 2025 meeting. I was told that such a meeting could interfere in the criminal investigation.\u201d<\/p>\n In an interview, Berry explained that Julian had talked to Slonim days earlier. \u201cJulian is a victim who has lost so much. But he was treated like a suspect,\u201d Berry said. During that interview, Slonim told Voller he needed to take his phone for a day. But the phone was never returned.<\/p>\n \u201cAfter several calls about it, we just gave up,\u201d Berry said.<\/p>\n Slonim did not respond to a request for comment.<\/p>\n Even though the phone was not returned, Slonim contacted him and instructed the lawyer not to produce Voller for a scheduled Cal-OSHA interview, Berry said.<\/p>\n Berry said the request was unsettling.<\/p>\n \u201cJulian cares deeply about getting to the truth and seeing that those responsible face justice,\u201d he said. \u201cIt was hard to understand why speaking to Cal-OSHA would be a problem.\u201d<\/p>\n Voller was not interviewed until mid-September. \u201cThe OSHA guys could not have been nicer, once we finally spoke to them,\u201d Berry said. \u201cThe same for ATF and the Yolo County DA, a class act. I did not have the same experience with Cal Fire.\u201d<\/p>\n Others said they were told not to talk<\/p>\n Berry and a state official familiar with Voller\u2019s account said he painted a troubling picture. Workers earned $20 an hour in cash and received no safety training, despite daily contact with explosives, often coming home after 12-hour days with blackened hands and faces after handling so many explosives.<\/p>\n In the days before the explosion, employees raced through the warehouse on a propane-powered forklift that occasionally leaked, loading and unloading black-market fireworks. Douglas Tollefsen, one of the five defendants facing murder charges, is said to have tested fireworks inside the warehouse \u2014 packed with explosives \u2014 months before the blast according to Berry and other sources.<\/p>\n Another family member of a victim said she was also instructed not to speak to Cal-OSHA.<\/p>\n Maria Melendez, whose husband Joel Melendez Jr. was killed, said arson and bomb investigator Slonim asked if she had been contacted by Cal-OSHA. \u201cI said yeah, they want to speak,\u201d she said.<\/p>\n Slonim, Melendez said, told her not to speak to Cal-OSHA.<\/p>\n \u201cIt felt very controlling,\u201d she said. \u201c…It just felt like he was interrogating me. It didn\u2019t come off very nice. I was 20-weeks pregnant, planning Joel\u2019s funeral, and he just kind of came at me. I don\u2019t know if that is just his personality, but the experience was troubling.\u201d<\/p>\n Melendez\u2019s second son Jeremiah \u2014 his late father\u2019s middle name \u2014 was born the day after Thanksgiving. She said preventing future accidents and ensuring those responsible face justice will be important to her sons..<\/p>\n Multiple investigations, time limit The arson and bomb investigators from Cal Fire played a prominent role in the Esparto case partly because the explosion happened on a compound owned by Machado, today charged with second-degree murder. This posed a conflict for Yolo County District Attorney Jeff Reisig because the county\u2019s enforcement agency was allegedly involved.<\/p>\n He asked the state attorney general to take over the case.<\/p>\n In a letter turning down that request<\/a>, Attorney General Rob Bonta placed his faith in Cal Fire.<\/p>\n \u201cWe understand that Cal Fire \u2014 not the Yolo County Sheriff\u2019s Office \u2014 is currently leading the investigation of this incident,\u201d he wrote. \u201cWe are confident Cal Fire is able to conduct a complete, thorough and unbiased investigation.\u201d<\/p>\n Cal Fire and Cal-OSHA officials met to yield better cooperation.<\/p>\n Michael Bright, who leads Cal-OSHA\u2019s Bureau of Investigations, wrote in an Aug. 8 email to Bryan Gouge, Cal Fire\u2019s chief arson and bomb investigator, that \u201cthere was a plan in place for Cal Fire to reach out to the individuals that need to be interviewed so the Cal-OSHA enforcement staff could complete their investigation.\u201d<\/p>\n Bright said in the email he believed \u201cit would be a good idea to schedule a meeting.\u201d<\/p>\n At that meeting the following week, , one attendee who wished not to be identified because they were not authorized to comment, said Cal-OSHA attorney Danielle Lucido stated that their investigators were still \u201cbeing blocked.\u201d<\/p>\n Cal-OSHA said that Lucido was not available for an interview at this time.<\/p>\n Addressing Cal Fire arson and bomb investigators Slonim and Bryan Gouge, State Fire Marshal Daniel Berlant appeared frustrated that problems persisted, the attendee said. The attendee said Berlant instructed Gouge and Slonim to do what was necessary to clear the obstacles.<\/p>\n Berlant did not respond to a question as to whether the arson and bomb inspectors had been ordered to block Cal-OSHA\u2019s efforts, or acted on their own. Cal Fire spokesperson Ricardo Coronado said in an emailed statement: \u201cDecisions regarding witness interviews and sequencing were made to preserve the integrity of the criminal inquiry.\u201d<\/p>\n Officials familiar with Cal OSHA\u2019s investigation said tensions with Cal Fire affected Cal OSHA\u2019s investigation to the extent where citations would have been higher than the $221,000 that was assessed, if there was more cooperation.<\/p>\n Why did it happen<\/p>\n Before the explosion, the same unit of Cal Fire missed warning signs about the company Devastating Pyrotechnics, whose principals have now been charged with second degree murder. The families of the victims have filed a $35 million claim<\/a> against Yolo County and state fireworks regulators alleging negligence.<\/p>\n Attorney Kyle Tambornini, who represents several of the families, said he understood the challenges Cal-OSHA experienced. But he said he has also been troubled by revelations that the team of Cal Fire investigators had missed what he called \u201cred flags\u201d pointing to serious problems with Devastating Pyrotechnics, which could have led to actions that would have prevented the tragedy.<\/p>\n Among the red flags, the team of arson and bomb investigators \u2014 Gouge, Slonim, Charles Elder and Nicholas Schroeder \u2014 seized hundreds of thousands of pounds of illegal fireworks dangerously overstuffed with explosive material in Commerce six weeks before the Esparto explosion.<\/p>\n Matt Voller, left, father of 18-year-old Esparto explosion victim Angel Mathew Voller speaks in Yolo Superior Court in Woodland on Thursday, April 16, 2026, during the arraignment of those indicted for the explosion. HECTOR AMEZCUA hamezcua@sacbee.com <\/p>\n
A framed photograph of Joel Melendez Jr. rests on his son Jeremiah Melendez, who was born in November 2025. Joel was killed on July 1, 2025 in a fireworks explosion in Esparto. MARIA MELENDEZ <\/p>\n
From left, defendants Craig Allen Cutright, Douglas Tollefsen, Jack Ying Lee and Sam Machado appear in Yolo Superior Court in Woodland on Thursday, April 16, 2026, for their arraignment. Tollefsen, operations manager of Devastating Pyrotechnics; Lee, show producer; Cutright; and Machado, a former Yolo County sheriff\u2019s deputy; face charges in connection with the Esparto fireworks explosion. HECTOR AMEZCUA hamezcua@sacbee.com <\/p>\n
Fireworks seized by state and federal authorities during a May 21, 2025 in Commerce, California. The brown boxes in the center of the photograph are \u201cQuick Draw\u201d fireworks, which contain more than 500 grams of explosive material and are illegal in California, according to fireworks experts who spoke with The Bee. Courtesy California Office of the State Fire Marshal <\/p>\n