The parents of a Valdosta teenager found dead at school inside a rolled up gym mat four years ago have filed a new lawsuit.

They're accusing dozens of people, including officials in the Lowndes County sheriff's office and school district, of covering up Kendrick Lamar Johnson's death.

One of them is Maryanne Gaffney-Kraft, a forensic pathologist at the GBI’s Macon crime lab.

The Johnsons accused her of failing to examine his body properly.

In January 2013, classmates at Lowndes High School in Valdosta found Johnson's body inside an upright wrestling mat.

Investigators concluded he got trapped inside the mat and suffocated, but his parents say classmates killed their son.

Earlier this year, a federal judge threw out their earlier lawsuit.

This latest suit was filed last week in Bibb County Superior Court.