VALDOSTA, Ga. (AP) — A federal judge has dismissed a lawsuit filed by the parents of a Georgia teenager found dead at school inside a rolled up gym mat.

News outlets report that U.S. District Court Judge W. Louis Sands filed an order Tuesday saying the parents of 17-year-old Kendrick Johnson were negligent in filing paperwork to the court and in filing for extensions. As such, the court dismissed their claims against 39 defendants without prejudice.

Sands also said the plaintiffs’ attorney was ignorant of a significant legal change tightening deadlines for certain paperwork.

Classmates at Lowndes High School in Valdosta found Johnson’s body inside an upright mat on Jan. 11, 2013. Investigators concluded he died in a freak accident. However, Johnson’s parents say classmates killed their son and law enforcement and school officials covered up the crime.