CANTON — A maintenance man and former Dahlonega resident who eventually admitted to sexually assaulting and killing a 7-year-old Georgia girl repeatedly denied any involvement with the crimes during his interrogation.

Video of a polygraph test and interview of 20-year-old Ryan Brunn, conducted five days after Jorelys Rivera disappeared, became a turning point in the investigation.

He had just begun a life sentence for the crimes when he used his sweatshirt to hang himself in his prison cell Jan. 19.

In the video, first obtained by WXIA-TV, Brunn appears nervous, pulling at his clothes and coughing as if to clear his throat.

"Did you cause the death of that girl?" a Georgia Bureau of Investigation agent asked him. Brunn repeatedly is heard answering "no" to variations of that question.

At one point, Brunn admitted he had lied to a detective about whether he had run a trash compactor where the child's body was found.

"I should have just told the truth straight up," Brunn told the agent. "But I didn't. I was scared."

Later, after the polygraph test was administered, the examiner told Brunn the polygraph showed that he was lying.

"Something is bothering you. It's written all over your face," the agent said.

"Nothing is bothering me," Brunn responded. "I'm not bothered at all. I'm not bothered at all."

Brunn later admitted in court that he had lied throughout the interview, and that he had molested and killed the girl at her Canton apartment complex.

Brunn had moved to Canton from Dahlonega just a month before Rivera's death.

Associated Press contributed to this report.