An initial autopsy showed Barnett was strangled.
Madison, 33, was arrested and jailed Saturday without bond.
He’s facing capital murder charges, according to the DeKalb County Sheriff's Office.
Sheriff Nick Welden released this statement:
“Due to the ongoing investigation, and in order not to jeopardize that investigation, I am not at liberty to disclose any additional information concerning this case. The road to justice for this sweet, innocent little girl is too important to release anything to jeopardize this investigation. I would like to thank our staff and all other departments that assisted on this case. This was a true joint effort, a team effort between multiple agencies who all worked tirelessly to help us get to this point.”
“Nobody should bury their 11-year-old child. Nobody should have hurt her,” the girl’s mother, Jonie Barnett, said.
Barnett fought back tears as she talked about her daughter.
“I couldn't have asked for a better daughter,” she said.
Barnett said her daughter loved science, and was caring and smart.
"Come and do it to me. Don't do it to her. Don't take my baby," she said.