A former teacher’s assistant accused of having sex with a 15-year-old student pleaded guilty to third-degree rape in Columbia County on Friday and was scheduled to be sentenced next month.

Christine Marie Johanson, 37, pleaded guilty to four counts of rape, court officials said. Sentencing was scheduled for October 3rd.

Johanson had already pleaded guilty to rape charges in Cowlitz County last month.

Columbia Co. Sheriff's Office/kgw.com photo

Christine Marie Johanson as shown in a police mug shot.

BACKGROUND: Teacher's aide crossed state lines to have sex with 8th grader

According to The Daily News in Longview, Wash., prosecutors hope she serves at least 30 months in prison.

Johanson used to work at Hudson Park Elementary School. She admitted to engaging in a sexual relationship with a freshman at Rainier Junior/Senior High School.