RANCHO CUCAMONGA (CBSLA.com) — The principal of a high school near Rancho Cucamonga has been accused of having sex with a former student.

Brian Garrett Joseph, 38, was arrested at his Corona home Tuesday after an investigation revealed the Etiwanda High School principal was intimately involved with the now 18-year-old girl.

The sexual relationship allegedly started when the victim was a student at the school.

Staff from the Chaffey Joint Union High School District contacted police on Monday with concerns about Joseph and the girl’s alleged relations.

The suspect was booked for unlawful sexual intercourse with a minor.

Joseph is being held on $25,000 bail.

He has since resigned from his position at Etiwanda High.

Investigators urged anyone who may have been victimized by Joseph to contact the Sheriff’s Department Crimes Against Children Detail at (909) 387-3615.