Oscar Enrique Santos, 45, of La Puente, was sentenced to 18 years in state prison, according to the Los Angeles County District Attorney's office.
Santos was convicted Nov. 10. 2011, of 21 felony counts including oral copulation of an incompetent person under 18 and sexual battery by restraint.
The former Garfield High School teacher's aide assaulted two girls with developmental disabilities, one of whom is confined to a wheelchair, between 2005 and 2007. During that time, Santos was responsible for assisting a gravely disabled male student.
The assaults took place on multiple occasions in an on-campus elevator while the girls, then ages 16 and 17, were between classes. The prosecutor said Santos would keep the elevator moving between floors while he carried out the attacks.
Santos also had a history of complaints from a third student, who testified that Santos unsuccessfully attempted to lure the student into the elevator.