The parents of a teenage girl are suing a school district and a high school principal in Pennsylvania for allegedly fostering a culture that allowed a 67-year-old teacher’s aide to repeatedly sexually abuse the child and “deliberately turning a blind eye,” according to their attorney.

Attorney Matt Casey filed a federal lawsuit Thursday against the Tredyffrin/Easttown School District and the principal of Conestoga High School in Berwyn, just outside Philadelphia. The alleged abuse, which began when the girl was just 15, occurred due to lax or non-existent policies within the district that allowed Arthur Phillips to groom the girl over several months with shopping trips and the like before ultimately sexually assault her, the lawsuit claims.

Casey also represents the parents of a teenage boy who was sexually assaulted by a 26-year-old teacher’s aide at the school who was sentenced to 11 to 23 months in prison last March. The abuse of the boy she tutored began when he was just 16 years old and much like Phillips, Christine Marie Towers treated her victim to restaurants and trips to the city, Casey said.

“The heartbroken parents I represent, and their children, are demanding accountability on the part of the Tredyffrin/Easttown School District, something that has yet to be achieved despite repeated, shocking instances of sexual abuse at Conestoga High School,” Casey said in a statement. “The already-known facts lay bare a school district custom of deliberately turning a blind eye to criminal acts in its midst.”

Parents of both children are also calling for the Conestoga High School principal, Amy Meisinger, to resign.

Several district officials and teachers knew of Phillips’ inappropriate relationship with the girl but failed to take action, according to the lawsuit — which claims another teacher at the school and her husband even joined Phillips and his victim on a double date to celebrate her birthday.

Phillips, who has been charged with statutory sexual assault, aggravated indecent assault, corruption of minors and related crimes, had been an instructional aide at the school since 2006, Philly.com reports.

The alleged abuse continued until the girl’s mother spotted Phillips in his car with her daughter near the family’s home despite the girl being on spring break, the lawsuit claims. Phillips was fired by the district the following week and he was later criminally charged.

The lawsuit seeks at least $75,000 in damages from the school district. A solicitor for the district told Philly.com that the accusations were false, although the district had not been served with a lawsuit as of Thursday afternoon, he said.

“We have yet to see any evidence anybody knew of a sexual relationship between the student and this former aide, nor have we been advised of any by the police,” district solicitor Kenneth Roos said.

Meisinger did not know about the inappropriate contact between the girl and an aide until several high school employees contacted police, he told Philly.com.

A message seeking comment from Meisinger was not immediately returned Friday.