VALDOSTA, Ga. (AP) — The parents of a south Georgia teenager found dead inside a rolled-up gym mat at school have filed a wrongful death lawsuit against school administrators.

The parents of 17-year-old Kendrick Johnson of Valdosta sued Monday in Superior Court. Their lawsuit blames the Lowndes County school board for allowing Johnson to die “at the hands of one or more students” while at during school hours.

Classmates found Johnson’s body inside a rolled-up mat propped in a corner of the gym Jan. 11, 2013.

Sheriff’s investigators concluded that he died in a freak accident, having fallen into the mat and gotten stuck upside down.

Johnson’s parents insist that someone killed him.

The school board’s attorney, Warren Turner, says in an email that the district has not been served with the lawsuit and that comment at this time wouldn’t be appropriate.