NORWALK (AP) - A Norwalk teacher has resigned and faces a sexual-exploitation charge after a recent high school graduate claimed she'd had a two-year relationship with him.

Warren County court documents show Ryan Christopher Janssen was charged Wednesday, three days after he admitted to school officials that he had a sexual relationship with the student. The school board accepted the 31-year-old teacher's resignation Monday.

Court documents allege he had a sexual relationship with the girl beginning when she was a 16-year-old junior at Norwalk High School. She contacted police when Janssen tried to end the relationship.

If convicted, he could face up to five years in prison.