CLARKSVILLE, Tenn. -- A Chad Youth Center internal memo reveals that an employee was kept on staff even though they knew he was abusive to children.

Video: Memo Reveals Youth Center Knew Of Abuse

John Thomas Boy led a troubled life, according to his mother.

That's why he ended up at Chad Youth Enhancement Center in 2004.

His mother said he was attacked by a resident counselor not long after his admittance.

"He was strangled, thrown up against the wall, kneed in the groin,” said Sharon Pruett.

The internal memo obtained by the I-Team shows that the same resident counselor had done the same thing two or three times in the past but that Chad kept him on anyway because they were understaffed.

"I would like for the facility to get shut down, if any way possible,” Pruett said.

The details are in a Serious Incident Report from the Department of Children’s Services. The trouble apparently started when Boy refused to come out of his room.

That's when the resident counselor, Calvin Lee Nelms, according to the report, picked him up by the collar of his shirt and threw him against the wall.

Other employees said they had to remove Nelms from Boy.

After the incident, Chad did not fire Nelms. According to officials, they told DCS they were looking into terminating him once they found someone to take his place.

More details are emerging about incidents that have happened at Chad over the years. Two teenagers have died there while being restrained by the staff.

Russell Kolins is a private investigator working for the family of Omega Leach, who died in June while a resident at the center.

"There were a lot of incidents at Chad that were investigated at DCS that were not brought to the attention of the police department,” Kolins said.

Nelms was arrested on suspicion of assault but the case has been expunged, meaning the records have been destroyed.

That means if Nelms were to apply for another job working with children, a potential employer would not find any record of this arrest.