A deadly fire that spread and killed two people in Northern California last year was set off by a man attempting to cover up a murder, investigators said Wednesday.

Victor Serriteno, 29, of Vacaville, had already been arrested last September and charged with killing 32-year-old Priscilla Castro. Her burned body was found on Sept. 2 near Lake Berryessa.

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Following an eight-month investigation into the origins of the Markley Fire, Solano County officials named Serriteno as an arson suspect.

In this photo from Sept. 11, 2020, Vacaville police arrest Serriteno in the murder of Castro.

In this photo from Sept. 11, 2020, Vacaville police arrest Serriteno in the murder of Castro. (Vacaville Police Department)

"Based on the extensive investigation, we believe Serriteno deliberately set the Markley Fire in an attempt to conceal his crime," the Solano County Sheriff’s Office said.

Castro had gone on a planned date with Serriteno in Vacaville on Aug. 16, but she was never heard from again, Vacaville police previously said.

Castro vanished after she on a date with Serriteno on Aug. 16, 2020, police have said. Investigators later determined the site where her body was found was also the origin of the Markley Fire.

Castro vanished after she on a date with Serriteno on Aug. 16, 2020, police have said. Investigators later determined the site where her body was found was also the origin of the Markley Fire. (Vacaville Police Department)

Two days later, a blaze dubbed the Markley Fire erupted in the area where Castro's body was found and merged with other fires to become the LNU Lightning Complex, which caused six deaths and destroyed about 1,500 homes and other buildings.

The Markley Fire merged with several other blazes to become the LNU Lightning Complex fire, pictured above, that spreadlast year in Vacaville, California.

The Markley Fire merged with several other blazes to become the LNU Lightning Complex fire, pictured above, that spreadlast year in Vacaville, California. (JOSH EDELSON/AFP via Getty Images)

Two of the Markley Fire victims — 82-year old Douglas Mai and 64-year old Leon "James" Bone — were found dead in their homes in unincorporated Solano County, investigators have said.

"We lost the lives of three people, countless structures, countless animals and property countywide," Vacaville Police Lt. Bryan Larsen said. "We’re thankful we were able to bring some closure to this portion of the investigation. And hopefully serve some justice for those who were affected by this fire."

The Markley Fire started on August 18th, 2020, in the Stebbins-Cold Canyon area and merged with the Hennessey Fire which was later included in the overall LNU Lightning Complex.

The Markley Fire started on August 18th, 2020, in the Stebbins-Cold Canyon area and merged with the Hennessey Fire which was later included in the overall LNU Lightning Complex. (Solano County Sheriff’s Office)

Serriteno was arrested on Wednesday and charged with arson and the two murders of Mai and Bone.

He has remained jailed without bail for Castro’s murder since September 2020. He has pleaded not guilty to her killing.

The Associated Press contributed to this report.