REDWOOD CITY — A 59-year-old high school Spanish teacher suspected of engaging in a two-year sexual relationship with one of his students has been charged with five felonies, according to the San Mateo County District Attorney’s Office.

Authorities say Hector Vazquez, a teacher at Westmoor High School in Daly City, started the illicit relationship with the girl during her sophomore year when she was 16. Vazquez, who lives in San Bruno, is accused of having sexual relations with the girl “on many occasions” at his home and other locations.

Vazquez made his first court appearance on May 9 and entered a not guilty plea to charges including three felony counts of unlawful sexual intercourse with a minor, sodomy with a minor and digital penetration by a foreign object, according to San Mateo District Attorney Steve Wagstaffe. A public defender was appointed to defend Vazquez, who is next scheduled to appear in court Thursday.

“What a betrayal of trust,” Wagstaffe said. “Parents view two places as safety zones for their children. One is their home. The other is the school they entrust their children to.

“Behavior like this betrays that trust at a very egregious level.”

Wagstaffe said authorities learned of the alleged relationship when a friend of the victim told school officials, who contacted Daly City police. Vazquez was arrested May 7 at his home.

Terry Ann Deloria, superintendent of the Jefferson Union High School District, said she was “horrified” to learn of the charges against Vazquez.

“It shook me to my core,” Deloria said. “Both as a superintendent and as a mom. We send our children to school expecting that that adults will keep our children safe. I was really horrified.”