Police say Courtney Keller, a paraeducator who supervised the school's detention program, began the sexual relationship with a 16-year-old sophomore two years ago. The sexual acts occurred both on and off campus, and the two had exchanged multiple inappropriate text messages, investigators said.
Keller immediately resigned in February when the allegations came to light. The victim, now an 18-year-old senior, is no longer a student at Black Hills.
Keller has since been arrested an booked for investigation of first-degree sexual misconduct with a minor.