If a בחור took off the door of his principle’s office before Purim, and now the Yeshiva is trying to figure out who did it, and the only one who knows is a בחור who, to begin with, didn’t really like that boy who took off the door. DO you know of any היתר for the ראש הישיבה to ask that boy? (Whatever the answer is, could you please write where you got that from, and who says that).
Rabbi Moshe Feinstein תשובה And the שבט הלוי are talking about a case that that boy they are asking who took off the door is not an enemy, the whole question was if it’s good חינוך to do that, on that we have a disagreement רב משה and others, but in a case that he does not like that boy they never spoke about that.(I am asking for halacha not halacha למעשה)
Since you are asking on a learning level please see the following attachment, taken from Mishnas Yisroel by R’ Yisroel Wanman shlit”a.