The parents of a Georgia teenager found dead inside a rolled-up gym mat two years ago have filed a lawsuit accusing classmates of killing him at school in a case that was covered up by school officials and investigators.

The wrongful death lawsuit filed by the family of 17-year-old Kendrick Johnson of Valdosta names 38 defendants, including three Lowndes High School classmates it says attacked Johnson on Jan. 10, 2013. Sheriff's investigators concluded the teenager died in a freak accident after becoming stuck upside down in the mat. No criminal charges have been filed.

Leigh Touchton, a former Valdosta NAACP president who has closely followed the case, says allegations in the lawsuit filed Monday are outrageous and unfounded.

Federal authorities are still conducting their own investigation launched in October 2013.