EL CAJON, Calif. -- A popular English teacher at West Hills High School pleaded guilty Thursday to sexually assaulting a 17-year-old female student last year.

John Christopher Holler, 42, is scheduled to be sentenced April 23 by El Cajon Superior Court Judge Patricia Cookson.

Holler pleaded guilty to one count of rape by a foreign object.

Holler could get up to three years in prison, but the judge indicated she would probably sentence the defendant to probation with local jail time, said Deputy District Attorney John Philpott.

There were no allegations that Holler engaged in sexual intercourse with the student, the prosecutor said.

Holler was arrested at his home last Nov. 9, following an investigation conducted by the San Diego County Sheriff's Department.

He was charged with two counts each of rape by a foreign object, attending an arranged illicit meeting with a minor and misdemeanor child molestation.

Philpott said the defendant and the girl had a "teacher-student relationship that became more as the summer went on, and in the last few months became physical and sexual."

A friend of the student told administrators about the relationship, and the student confirmed the acts had occurred, authorities said.

Defense attorney Robert Boyce said the physical activity involved just one incident.

Holler, who has worked at West Hills High for 15 years, was placed on administrative leave after his arrest.