Editor's note: An earlier version of this story identified Reiko Matsumura as living on the Esparto property. It has been corrected to say Matsumura is connected to the property.
A decade-long criminal conspiracy. An illegal enterprise that imported more than 11 million pounds of black-market fireworks across Northern California—one million pounds of which were on the ground when the lives of seven people ended in an instant.
That is how prosecutors at the Yolo County District Attorney’s Office on Friday characterized the operations at a fireworks warehouse in Esparto that exploded on July 1, 2025.
District Attorney Jeff Reisig called the scale of the investigation “massive,” and said in his 20-year career “it has been the largest we’ve ever undertaken.”
Deputy District Attorney Clara Nabity said last week a county criminal grand jury returned two indictments tied to the deadly explosions. The most serious charges include seven counts of second degree murder — one for each of the victims — filed against five defendants.
The victims were:
- Christopher Goltiao Bocog, 45, of San Francisco
- Neil Justin Li, 41, of San Francisco
- Joel Jeremias Melendez, 28, of Sacramento
- Carlos Javier Rodriguez-Mora, 43, of San Andreas
- Jesus Manaces Ramos, 18, of San Pablo
- Jhony Ernesto Ramos, 22, of San Pablo
- Angel Mathew Voller, 18, of Stockton
Those indicted for murder are Kenneth Chee, Jack Lee, Gary Chan, Douglas Tollefsen and Samuel Machado, a lieutenant in the Yolo County Sheriff’s Office. Nabity said the grand jury believed they were “responsible for the initial deadly explosion,” which prosecutors said happened on the eastern side of the property owned by Machado and his wife Tammy.
This was the location of the operations of Devastating Pyrotechnics, which was owned by Chee. Prosecutors said the indictment identified him as the leader, along with Lee and Tollefson, with the aid of Chan.
The indictment also includes multiple counts of felony conspiracy against seven individuals. Nabity said the charges allege a “decade-long conspiracy” which turned the Machado property into the “Northern California hub for an illegal enterprise that imports and sells illegal explosives on the black market.”
“They are devices that have so much more explosive fireworks than the law allows, that they can’t be considered fireworks,” Nabity said.
Several counts of the indictment specifically highlighted Samuel Machado’s alleged participation. Nabity said this included his role in the sheriff’s office “to help shield the conspiracy as it expanded.”
According to the indictment, Machado authorized Chee to conduct Devastating Pyrotechnics operations on his property starting in 2015, when there were 13 storage containers on the site. By 2025, prosecutors allege, the footprint had grown to more than 50 storage containers and a 5,000-square-foot warehouse.
Over the decade, the indictment states the enterprise imported more than 11 million pounds of explosives and related materials — one million pounds of which were stored on the Machado property on the day of the blast.
Nabity said the illegal explosives were designed and packaged for consumer sale under private labels. The indictment identifies those brands by defendant: Chee imported devices under the label “Bean Day Ho,” Tollefsen imported explosives branded “For the Streets” or “FTS,” Ronald Botelho III imported devices under “Big Bully” and “Bad Dad,” and Craig Cutright imported explosives branded “Double OG.”
Cutright and Botelho were also identified as being part of Devastating Pyrotechnics, but the former also owned the separate company Blackstar Fireworks, which started in 2023 and also operated from the Esparto property.
Cutright is also still listed as a volunteer member of the Esparto Fire Protection District and was put on leave after the explosion.
Several of the indictment counts were also related to licensing issues. Prosecutors said while some of the individuals held licenses issued by the federal Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) and Cal Fire, “not one storage container on the property was licensed by ATF.”
Chee had applied to the ATF for “relief from disabilities” under the Federal Explosives Law, but this was rejected in March 2009 “due to Kenneth Chee’s disabling convictions or other factors.” The San Francisco Chronicle previously reported a prior criminal conviction in the 1990s made Chee ineligible to receive or possess explosive materials or be issued a federal explosives license or permit.
Prosecutors said Lee secured ATF Federal Explosives Licenses for importing, exporting and manufacturing fireworks in January 2011. These were transferred to Chan, the Operations Manager for Devastating Pyrotechnics, in September 2014.
Nabity said while Chee held Cal Fire licenses, they did not authorize "importing or possessing or selling explosives that are labeled 1.3G,” referring to a classification of professional-grade fireworks regulated by the ATF. She also said there are no Cal Fire or other licenses “that permits the storage of explosives near homes and public roadways.”
Yolo County officials previously said they had never issued licenses, permits or approvals for either Devastating Pyrotechnics or Blackstar Fireworks to operate in Esparto. The county has banned fireworks businesses since 2001.
The indictment also alleges Machado and Cutright made false statements to local and county government officials about a warehouse constructed on the property, and that Machado signed a building permit exemption in 2021 falsely stating the structure would only be used as an agricultural building.
Yolo County Deputy District Attorney Clara Nabity (right) and District Attorney Jeff Reisig (center) speak at a news conference Friday, April 10, 2026, in Woodland, Calif., to announce indictments in connection with the July 2025 Esparto explosion.Greg Micek/CapRadioThe indictment detailed a host of other criminal charges against the defendants, possession of materials to make explosives or destructive devices, weapons possession and tax fraud.
Tammy Machado, who is an administrative employee at the Yolo County Sheriff’s Office, also faces five felony counts detailed in a separate indictment:
- Mortgage fraud
- Two counts of willfully false returns
- Child endangerment
- Animal cruelty
Nabity said the child endangerment and animal cruelty charges were connected to a “substantial volume” of explosives stored near a family pool, as well as the million pounds of material stored near the family residence. Samuel Machado faces the same charges.
Sheriff denies knowledge
Speaking shortly after the indictments were released, Yolo County Sheriff Tom Lopez said he had no knowledge of the illegal fireworks operations on the Machados’ property.
Lopez revealed that both Samuel and Tammy Machado submitted resignations on March 17, which he accepted. They had been put on leave after the explosion “to give more integrity to the investigation.”
He also said the sheriff’s office was conducting a third-party internal investigation, but declined to give additional details.
The sheriff’s office recused itself from the Esparto case itself due to the connections with the Machados. Lopez said Friday that, “there is no win for anybody if my agency were to conduct that investigation because it would always be challenged that it was done properly or not, depending on how the results came out.”
Asked whether he knew about the operation or illegal weapons stored on the property, Lopez said he did not.
“It’s not something I would expect one of my employees to be doing,” Lopez said.
A Yolo County civil grand jury report released last month asserted the sheriff’s office failed to enforce existing fireworks ordinances and did not adequately review documented outside employment by sworn officers, among other systemic failures.
It also noted a third former sheriff’s office employee is connected to the property — Reiko Matsumura, Tammy Machado’s sister.
Their late father, Jerry Matsumura, was described by the grand jury as being an active member of the Western Pyrotechnics Association and known for putting on fireworks displays. He was also a fire commissioner with the Esparto Fire Protection District.
The report also said one of Matsumura’s former business partners was Kenneth Chee, of Devastating Pyrotechnics.
Reiko Matsumura was placed on unrelated disability leave before the July 1 explosion and retired in September 2025. She has not been charged in connection to the tragedy.
The investigation continues
Prosecutors said at least five people are booked in the Yolo County Jail and will be arraigned on Monday. Jail records show Samuel Machado was in custody at the Sutter County Jail as of Friday afternoon, while Chan was reportedly booked in Santa Clara County.
Chee was taken into custody on Thursday in Orange County, Florida on a fugitive from justice charge and Botelho is in custody in Del Norte County, where he was arrested in December in connection to the Esparto explosion.
“They will eventually be brought back and then arraigned, and joined into the case,” Reisig said.
Tammy Machado is the only defendant not in jail as of Friday afternoon. She was bonded out Thursday after being arrested.
State Fire Marshal Daniel Berlant’s office released a statement to CapRadio Friday stating he is “encouraged to see this case continue to proceed towards justice,” and is ready to support the DA’s office as necessary.
“As we approach the 4th of July, I must reiterate our zero tolerance towards illegal fireworks,” Berlant’s statement concluded.
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