OROVILLE, Calif. - A former Las Plumas High School teacher pleaded guilty on Wednesday in Butte County Superior Court to two counts of unlawful sexual intercourse with two 17-year-old students, according to District Attorney Mike Ramsey. Lindsay Himmelspach, 33, is scheduled to be sentenced on June 15, and faces three years and eight months in prison. Ramsey added she may also be required to register as a sex offender. Oroville Union High School District Superintendent Corey Willenberg met with investigators on October 30, 2015, to report a possible inappropriate relationships between students and Himmelspach. According to officials, the investigation began when the school received an anonymous call about the alleged inappropriate relationships. Investigators went to Las Plumas High School and said they found out Himmelspach had sexual relationships with two students over the summer of 2015. One student was from Prospect High School, the other from Las Plumas High School. According to deputies, these sexual relationships were brief and happened during the summer break; however, they included sharing nude photographs between Himmelspach and the two victims. Himmelspach has taught at Oroville and Las Plumas high schools, and has been teaching for about 10 years, deputies said. She was arrested on October 30 at Las Plumas High School and transported to the Butte County Jail where she was booked for two counts of unlawful sexual intercourse with a minor, two counts of communicating with a minor for the purposes of committing sexual acts and two counts of communicating with a minor to commit lewd or lascivious acts.