A judge in Spencer, Tennessee has sentenced a former high school teacher to 15 years in prison for having a sexual relationship with a student.

Johnny Lee McElroy entered guilty pleas Monday at the Van Buren County Courthouse to multiple charges of statutory rape and sexual battery by an authority figure.

The 55-year-old McElroy will have to serve about 30 percent of his time to be eligible for parole.

Prosecutors say McElroy had known the girl since the sixth grade and groomed her for sex, which began when she was 14. Investigators say the victim wasn't in McElroy's classes at Van Buren County High School, but was a sophomore there.

Prosecutors say there were many sexual incidents -- some of them at the school.