I am going to have to disagree. He is not the one in business, you are. If it is the first time something like this has happened I would give a warning to be more carefull, writen warning. Employees don't like it when you mess with their checks, they sometimes will end up getting more back from you. Maybe it was not his fault, he is lucky it did not come down and kill himself or someone else.
I know this topic is probaly going to get heated as this topic has in the past, the bottom line, it is against the law to take money out of someones check without proper written notice, it is to bad more people do not know that.