and our store manager threatened him and kicked him out.
As difficult as it may be in the heat of the moment, the best thing to do in this circumstance is to initially act like nothing is wrong, and then quietly alert the authorities ASAP. If you just kick them out, they’ll find someone else to do the work, but they’ll be more careful with that next person. You don’t want to scare them into the wind, because then investigators will have a much harder time.
If you’re paying a school $20k per semester, they can afford to eat the cost on some paper and toner.