Mancini allegedly told the boy he was traveling to Atlanta and that he wanted to meet in person.
"The boy realized over time this was a dangerous path, so he notified his mother," Derick Booth, a spokesman for the Hall County Sheriff's Office, said.
“Our investigators assumed the boy's identity online, and continued the conversation,” Booth said.
Mancini agreed to meet at a strip mall, but when an unmarked car pulled up, he allegedly drove away.
Investigators, posing as the 13-year-old, contacted him again.
"That's when he said, 'I got spooked. I do want to meet you.' That's where our investigators made contact with him," Booth said.
Mancini was arrested on the spot and charged with criminal attempt to commit child molestation.
Mancini was an assistant coach at Cathedral Prep, a Catholic school in Erie. He was also a substitute teacher at Cathedral Prep and Villa Maria Academy until 2015. School officials said he passed all of his background checks, but when they learned of the arrest, he was fired.
"Prior to his arrest, there were never any reports of inappropriate behaviors with minors," school president Father Scott Jabo said in a letter to parents said.