Molly says, "I didn't steal anything.   I can't believe you think I did.   I thought you were my friend.   Yes, I went into Alex's room. ... I left him some brownies.   I didn't want him to know who they were from."   You remember about Alex's secret admirer who left him little presents and realize that that explains what you saw and why Molly has been acting strangely.   You tell Molly that you haven't told anyone else about seeing her and that you are very sorry you suspected her.   She accepts your apology and says that she will explain to the Campus Police why she was there.   The Campus Police interview everyone in the group, and people complain about the waste of time and their harsh tactics.   No one is ever caught, but the thefts stop.
( End of scenario)