I you decide to keep him there, and it sounds as though you may not have much choice, at the very least you should have a sit down with the powers that be and ask what procedures they are going implement to keep this from happening again. As mentioned you could report it to whatever agency oversees nursing homes, but I would first sit down with the home and get their response.
Yes, in my experience, many of the workers are paid a minimum and there tends to be a lot of turnover in employees. A very tough job imo.