The father of an autistic New Jersey boy whose alleged humiliation at the hands of school staff was caught on tape is demanding his son's teacher be fired, but the state teachers' union said her voice is not on the recording.

Stuart Chaifetz sent his 10-year-old son Akian to the Cherry Hill school with a hidden microphone, which allegedly recorded staff in teacher Kelly Altenburg's classroom berating the boy and calling him a "bastard." A video Chaifetz made describing the abuse along with audio went viral. The district claims it took action against "the individuals involved" in the incident, but won't say whether Altenburg is one of them. Multiple adult women's voices can be heard making inappropriate and even cruel comments on the tape, which Chaifetz released as part of a viral video blasting the district.

"It was hell ... They were destroying my son," the father said of the February incident

Attorneys for Altenburg, a 25-year special education teacher, released a statement Thursday claiming she has been misrepresented in reports of abuse in the classroom.

The statement said Altenburg was in a Professional Learning Community Meeting that morning and had not been in the room with Akian for an hour that morning.

"Mrs. Altenburg does not condone any such remarks... and this language was not used at her direction, in her presence or with her knowledge," the statement said. "Mr. Chaifetz'(s) comments to the contrary are totally inaccurate."

Although Chaifetz said he believes the teacher was involved in his son's torment, a spokesman for the New Jersey Teachers Association said Altenburg "appears to have been exonerated from making the offending comments," which included conversations about a hangover as well as abuse directed at the boy.

"The teacher’s voice is not on that recording," said NJEA spokesman Steve Wollmer. "It’s not her voice. It’s a teacher aide and somebody else.

"If she had been heard making those statements, I am sure she would have been terminated," he added.

The Cherry Hill Public School District would not confirm the names of anyone heard on the recording. But the district said in a statement Tuesday that "the individuals who are heard on the recording raising their voices and inappropriately addressing children no longer work in the district and have not since shortly after we received the copy of the recording." In a subsequent statement, the district said it "disagrees" with Wollmer's claim Altenburg had been "exonerated.

"While we cannot legally comment specifically on personnel matters, the District does not consider the matter closed at this time as the investigation remains ongoing," the statement said.

Chaifetz believes Altenburg should be fired. He believes Altenburg has been transferred from Horace Mann Elementary School, where his son attended class, to another school in the district soon after administrators obtained the seven-hour audio recording. He said he believes teacher tenure protected Altenburg from getting fired. Wollmer insisted that Altenburg's tenure, which protects experienced teachers from being punished without a show of cause, has nothing to do with it.

"If she had been heard making those statements, I am sure she would have been terminated," Wollmer said.

Superintendent Dr. Maureen Reusche could not be reached by phone Thursday to clarify the matter.

Chaifetz planted the secret digital audio recorder on Akian on Feb. 17, after he suspected Altenburg and a teaching assistant were bullying the child at school. Chaifetz said he had been receiving reports that the boy was hitting his teacher -- a claim he said "didn't make any sense to me because that’s not my son."

"I knew, as a father, that there was something going on inside that classroom that was affecting Akian badly enough that he would be hitting a teacher," Chaifetz told FoxNews.com.

When Chaifetz later listened to the tape, he and his ex-wife were "shattered," he said. He believes the tape demonstrates that their son was being subjected every day to a "culture of cruelty."

"With the exception of recess, it was a nightmare day," said Chaifetz.

The father said that Altenburg and her assistant took advantage of his son and the four other autistic students, knowing that the disabled children were unable to complain to their parents.

"Would they have called my son a 'bastard' if they knew he could come home and tell me?" he said. "They thought I would never find out."

Chaifetz claims district officials told him a teaching assistant he identified as Jodi Sgouros was fired immediately after administrators listened to the recording in February. But he says he received no word about any punishment meted out to Altenburg. Wollmer told FoxNews.com Altenburg has been reassigned to another school in the district.

Unsatisfied with the district's handling of the matter, Chaifetz went public with the tape. He posted a 17-minute long video on YouTube titled "Teacher/Bully: How My Son Was Humiliated and Tormented by his Teacher and Aide," which has so far received more than 3 million views. He then posted a follow-up YouTube video on Tuesday, calling out school officials for not firing Chaifetz.

"As far as I know, she is working with the high school," he told FoxNews.com. "She clearly was working at the high school after I gave them the audio because she had a voicemail there."