A Philadelphia teenager with cerebral palsy is recovering after a brutal attack in which she was bitten across her back and shoulders. However, from where the bites originated remains a mystery.

16-year-old Ariel Alexander’s condition has confined her to a wheelchair for most of her life, leaving her unable to communicate to authorities about who committed the savage act, MyFoxPhilly.com reported.

Yet the human bite marks across her left shoulder and upper back are clearly visible.

Ariel’s parents reportedly believe that the incident occurred at MLK High School, where Ariel is a student in a special needs classroom. Her parents say that a few days after the attack, which they claim took place on May 1, a male teacher took them to one side and informed them that a fellow student was responsible. The school rejects the notion that it occurred on school property, stating that all teachers interviewed have denied seeing anything.

"It could not have happened at school, and if it could have -- if for some reason something happened-- someone would have seen it," Fernando Gallard, school district spokesman told MyFoxPhilly.com.

The school district has reported Ariel's injuries to Philadelphia's Department of Human Services, which is investigating the incident as a possible case of child abuse.

Randell Alexander, Ariel's father, said the DHS has already interviewed him and his wife about the possibility that the bites were inflicted by Ariel’s 17-year-old sister, who also has special needs.

"They gonna try and pass the buck, say it happened here. No way, impossible," Alexander told MyFoxPhilly.com

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