Rainer Reinscheid, 48, is now facing eight charges of arson and one count of attempted arson. Prosecutors said he set the fires as revenge following the suicide of his 14-year-old son, Claas Stubbe, who killed himself after being disciplined at school.
Fires were set at University High School in Irvine, an assistant principal's home and the park where the teen hanged himself. The assistant principal had disciplined the boy for allegedly stealing from the school store.
Reinscheid is also suspected of sending emails about plotting a deadly attack on the school. Reinscheid wrote that he would shoot at least 200 students and administrators, commit sexual assaults and burn down the school before killing himself, Orange County deputy district attorney Andrew Katz said. Investigators said they found evidence of online searches about explosives, guns and ammunition.
Reinscheid was arrested in Irvine on July 24. He posted bail but was re-arrested three days later after authorities found the emails with the details of his alleged mass-murder plot.
The Associated Press contributed to this report.