The Philadelphia District Attorney's office says 56-year-old Mark Williams sexually assaulted a 17-year-old student at the school.
Williams has been charged with Institutional Sexual Assault of a Student, Unlawful Contact with a Minor, Corruption of a Minor, Endangering the Welfare of a Child and Interference with the Custody of a Child.
The case is still under investigation, and anyone with information on Mark Williams is asked to call the Philadelphia Police Special Victims Unit at 215-685-3251.
