Octavia Walton, 40, was arrested around 11:10 a.m. Thursday at 2710 Webb St. in Vallejo.
Walton was booked into Solano County jail for arson of an inhabited structure, possession of arson material, using an explosive device, using an explosive device to terrorize, and conspiracy to commit a crime. Her bail is $121,666, according to the jail booking log.
Benjamin Stickel, 31, of Vallejo, was arrested for the arson around the same time in Solano County jail. He also faces separate charges including failure to appear, possession of a hypodermic needle, possession of stolen property and vehicle theft, Solano County sheriff's Sgt. Walt Gilliam said this morning.
Stickel and Walton are acquaintances, Gilliam said. Walton has been arrested before by Vallejo police, but not for arson, he said.
Vallejo firefighters responded at 4:10 a.m. on June 30 to the fire at the courthouse at 321 Tuolumne St.
The three-alarm fire caused extensive damage to the court's criminal division offices, burning files, furniture, computers, and wiring in addition to causing smoke damage in the courtrooms.
Firefighters from Crockett, Benicia, Napa and the Cordelia Fire District also responded.
At the time of the arson, Vallejo Fire Department spokesman Bill Tweedy gave an initial damage estimate as being between $100,000 and $300,000.
Walton and Stickel will be arraigned at 1:30 p.m. Monday in Department 21 of the Solano County Justice Center in Fairfield.