(Hillsboro, OR) -- A former teacher's assistant has been sentenced to prison for sexually abusing a student. Last month, Yessenia Manriquez-Casillas, pleaded guilty to two counts of sexual abuse in the second degree. She was a teacher's assistant at Century High School in Hillsboro when she arranged a meeting with a teenage student. They drove to another location where the sexual abuse occurred. The victim's mother found text messages on the child's phone from Manriquez-Casillas and the child disclosed the abuse. Manriquez-Casillas was sentenced to 13 months in prison.