PLACER COUNTY -- A former Nevada County school teacher was arrested Thursday after Placer County detectives found evidence that she had sexual relations with a minor, officials said.

Placer County detectives began investigating the relationship September 30, and found that Gina Holbrook, 45, and the 17-year-old boy had a sexual relationship for nearly 8 months, dating back to late 2015. During the relationship, officials say Holbrook was a teacher in the Nevada County School District, but was not the teen's teacher.

The district confirmed to the sheriff's office that Holbrook is no longer an employee.

Holbrook is facing charges of unlawful sexual intercourse with a minor, oral copulation with a minor, and digital penetration with a minor. Sheriffs say Holbrook was released on $75,000 bail.