I think their intentions do directly influence the questioning of a student in that school.No, their intentions have no bearing on the law. Under the conditions described, and absent an immunity deal (which would require coordination with the DA’s office and preclude any rush to obtain his statement to the exclusion of his parents), his right to remain silent is unassailable. When a sworn officer conducts an interview, it is to support enforcement of criminal law. That is literally their function. They may conclude that no law was broken, but that doesn’t invalidate a subject’s 5th Amendment rights.
And yes I misspoke when I said their 5th Amendment rights are inviolate. If an officer of the court enters into an immunity from prosecution agreement with the subject, they may be compelled to provide a statement. Otherwise, no.