One of last August's wildfires that merged with others to become the LNU Lightning Complex fires is now believed to have been the result of arson — and the culprit, according to the Solano County Sheriff's Office, is a 29-year-old man who likely set the blaze to cover up an earlier murder.

The Markley Fire, which broke out on August 17 near Monticello Dam, had an origin point very close to where authorities later discovered the body of 32-year-old Priscilla Castro, on September 2. On Wednesday, a 29-year-old Vacaville man, Victor Serriteno, was arrested and charged with Castro's murder following an eight-month investigation, as the Associated Press reports.

"We believe Serriteno set the fire in an attempt to cover up his crimes," said Solano County Sheriff Thomas Ferrara during a Wednesday press conference.

As the Daily Republic reports, Castro's family in Oakland reported her missing on August 18 after not hearing from her for two days. The investigation found that she had met Serriteno online and traveled from Vallejo to Vacaville on August 16 to meet him for a date. Her abandoned vehicle was then found by Vacaville officers on August 18, on the 100 block of Bush Street.

It wouldn't be until September 2, after the fires died down, that investigators would use cellphone records to create a search grid and discover Castro's burned remains near Lake Berryessa, and near where they believed the Markley Fire had begun.

The fire would ultimately merge with the Hennessey, Spanish, Green, Gamble, Round, and Aetna fires to form the eastern portion of the LNU Lightning Complex, which grew to become the fourth-largest wildfire in recorded California history. The complex burned 363,220 acres in total, 192,000 of which were in the Hennessey portion of blaze, with other fires like the simultaneous Walbridge Fire in Sonoma County accounting for the rest. A total of 700 structures, including 309 homes burned in Solano County as a result of the fires.

Map via Solano County DA's Office

Within what's considered the Markley Fire zone, two other people were killed by the fire itself: 82-year old Douglas Mai and 64-year old Leon "James" Bone. Both men were found dead inside their homes in unincorporated Solano County, as shown in the map above, and they died on August 19 after the fire came down the Vacaville foothills.

Serriteno has been in police custody since September 11, when he was arrested in connection with Castro's death. He pleaded not guilty to her murder.

He'll now be arraigned Friday for the murders of Mai and Bone, as well as the burning of their homes. As the Daily Republic reports via jail records, he's been charged with two counts of first-degree murder and one count each of arson of an inhabited structure, as well as arson during a state emergency, and an arson enhancement to the murder allegation.

Related: Fire Updates: LNU Damage Map Released, SCU Complex Grows Overnight

Photo by Justin Sullivan/Getty Images