By Tim Jimenez

PHILADELPHIA (CBS) — Philadelphia’s District Attorney’s Office is charging a former high school employee with having sex with a student.

56-year-old Mark Preston Williams turned himself into police Tuesday morning. Authorities say Williams had sex with a 17-year-old student of Northeast High School in Northeast Philadelphia.

Williams’ role at the school is unclear. The DA’s office says he was the former Dean of Students at the school, but the school district says he was a staff member in that office and none of the contact happened on school grounds.

Whatever the case, District Attorney spokeswoman Tasha Jamerson says Williams is facing serious charges, including a third degree felony.

“Institutional sexual assault, Unlawful contact with a minor,” she says, “Corruption of a minor. Endangering the welfare of a child and interfering with the custody of a child.”

Police are still investigating and ask anyone with information on Williams to call the Special Victim’s Unit at 215-685-3251.

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