A college professor charged with arson for allegedly setting a series of fires at an Orange County high school his son once attended was plotting to kill students and teachers, then burn down the campus after his son committed suicide, authorities said Tuesday.

Rainer Reinscheid, 48, was expected to appear in court Tuesday afternoon after he was charged with five counts of arson, one count of attempted arson and a misdemeanor count of resisting or obstructing a police officer. If convicted, he faces up to nearly 13 years in prison.

Authorities planned to ask a judge that he be denied bail.

Prosecutors said Reinscheid started five fires at University High School earlier in July.

His son had been a student there and had been disciplined this past spring before he committed suicide at a park preserve.

Reinscheid was arrested last week in connection with the fires and posted $50,000 bail.

After he bailed out, authorities found emails on his cell phone describing a plot to burn down the high school, commit sexual assaults and purchase weapons to murder school officials and students there before killing himself, said Orange County District Attorney spokeswoman Farrah Emami.

Prosecutors believe Reinscheid was acting alone but it wasn't clear if he was targeting anyone specifically.

"I can only at this point tell you, he laid out in sufficient detail plans to purchase guns and murder lots of people," Orange County Deputy District Attorney Andrew Katz told The Associated Press.

After the emails were discovered, Emami said Reinscheid was arrested again.

"The emails by themselves do not support a criminal charge but they do support our argument that he should be denied bail because he's dangerous" Emami said.

Reinscheid is a professor of pharmaceutical sciences at the University of California, Irvine, and has been there for about 12 years, said a university spokeswoman, who referred further comment to authorities.

It wasn't immediately known if he had retained an attorney.