(Hillsboro, OR) -- A special education teaching assistant at Hillsboro's Century High School has been indicted and arrested for alleged sexual abuse of a student. The Washington County Sheriff's Office says 22-year-old Yessenia Manriquez Casillas is accused of picking up a student at a celebration and sexually abusing them. Manriquez Casillas is charged with four counts of sexual abuse in the second degree. Detectives were told there may be additional victims. They should contact the Washington County Sheriff's Office.