Not exactly. Other than DB always getting fired.
Do you think he is joking or semi-serious about his comments? Just the fact he is making them is worrisome. If you think he might be serious, talk to someone higher up about it. Maybe even report it to the police and ask for some extra drive bys in your neighborhood for a couple weeks after you let him go. Just to be safe.
When you do let him go - because of his behavior, I would not give him warning and send him home immediately. You do NOT want to give him a chance to mess anything up. He might find it amusing to change a prescription that could then kill someone.
People we have worked with and kind of let go have been messy, but they didn't live anywhere near us. I wasn't the one giving the killing blow though. We tried to keep working with some on a different basis, but they were not interested. That's not an option for you anyway.
I would be sure to explain to him WHY you are letting him go. So that "hopefully" he matures a bit and does better at his next job. I would explain to him the problems before telling him he is fired, because after you say bye bye he won't be listening.
My one question is - have you talked to him about his unacceptable behavior yet? So that he has had a chance to change his behavior? It's extremely annoying to be fired and not know what you did wrong that got you fired. And had it been something you could have changed had you known what needed fixing, it's even more annoying.