It is not unlawful for a law enforcement official to ask a child questions without first locating and causing the presence of the parent. In many circumstances, this will be fully responsible and professional conduct. And such conduct is not made unlawful by the presence of the school principal -- just the opposite. Moreover, it is doubtful that the room was locked, most likely the door was closed and that is not per se inappropriate. In all events, that element is not likely to be a determinative one as to the legal issues here.
Now, you have left out ALL the details about the "terrorizing" and the "bullying," so there is nothing of use that can be offered on those issues. Clearly the facts and circumstances of how your daughter was treated during this questioning are critical. For example, if she was beaten into unconsciousness, there is a serious legal problem. But in the absence of any of the facts that underlie your accusations, no one here can tell you anything reliable. You can re-post or you may want to consult with a local civil rights attorney.
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