My son is 12 years old. He goes to Wakefores-Rollesville Middle Scholl in North Carolina. A classmate is acusing him of leaving a voice message on the other kid's cellphone threatening to kill him. The school guidance called me and said he heard the voice message and could not identify the voice as my son voice. He also said the call was made on Saturday at 5:17pm. The following day the assistant principal called me and said the call was made on Sunday at 12:57pm and that he could not recognize the voice on the message but that there were more kids talking on the background.
I called the mobile phone company and requesed a report of the calls made out of my son's cell phone from Friday to Monday. There is not such a call to that cell phone number during the time and dates the guidance and the assistant principal has mentioned.
However, my son told me that the assistant principal is harrasing him every time he sees him in the lobby or at lunch telling him "You know you did it, you know you did it. Confess!"
Is this legal? What are my son's right? Does the Miranda rights applies here? What should I do? We are hispanics.
Please help me understand.

