The Georgia sheriff who has spent the last few years investigating the death of Kendrick Johnson offered $500,000 of his own money Monday (Jan. 31) as a reward for information leading to a conviction in the 17-year-old’s 2013 death, fending off criticism of his investigation from Johnson's family.

“After the release of my synopsis of the federal files on the Kendrick Johnson case, his parents have called me a liar and continue to state that Kendrick was murdered,” Lowndes County Sheriff Ashley Paulk wrote.

“Because of these statements, I am personally — with my own funds — offering a reward of one-half million dollars ($500,000) to anyone who comes forward with information that results in the arrest and conviction of a person for the alleged murder of Kendrick Johnson at Lowndes County High School.”

Paulk, who wasn’t sheriff when the teen died, conducted a second local investigation into Johnson’s death. His report, released on Jan. 26, said the death was accidental and closed the probe without filing criminal charges.

Johnson was a sophomore at Lowndes County High School in Valdosta, Ga., where his body was found upside down in a wrestling mat on Jan. 11, 2013. An initial investigation determined that he died of asphyxiation after accidentally slipping into the center of the mat when trying to retrieve his sneakers.

The Lowndes County Sheriff's Office reopened the case in March amid allegations of a cover-up and discrepancies in the case.

Johnson’s family, who never accepted that his death was an accident, rejected the sheriff’s report. The teen’s father, Kenneth Johnson, held a press conference on Jan. 27 outside the sheriff’s office.

"Do not believe anything that this sheriff's department tells you,” he said, vowing to “fight as long as I have to.”

Kenneth Johnson pointed to alleged discrepancies in the investigations, conducted by local, state and federal agencies, and discrepancies among the multiple autopsies performed on his son.

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An autopsy conducted by the Georgia Bureau of Investigation concluded that Johnson died of asphyxiation. But a private autopsy requested by the family found that the teen died of “non-accidental” blunt force trauma to his neck, leading them to believe foul play was involved.

Kenneth and Jacquelyn Johnson, Kendrick’s parents, filed a wrongful death lawsuit in 2015 against three individuals, alleging that they killed their son. They also charged that the death was covered up by Lowndes County school and law enforcement officials. But a judge in Lowndes County Superior Court ruled against them.