Why are you coming onto a gaming forum to discuss this??? You tell us you're the manager aren't you?
What country do you live in? Did you give him a talk or any warnings before you fired him or did you do it in a sudden manner? I'm just trying to understand what he's thinking. Was he really trying to do better or was he just one of those lazy types? I've never been fired before so i'm sure it hurts, and you'd be mad too. In the past if I knew a job wasn't going to work out or I didn't really like the employees I would quit to save my dignity and time.
I'm not sure what kind of policies your running in that store or what your procedures are for employee termination but employees do have rights. He could bring a wrongful dismissal case against you. It sounds like your business isn't very legit.
