I've read so many horror stories about people who invite people into their home and have bad things happen that I'd never invite anyone to stay with us! But then in saying that, what happens to trusting the kindness of strangers, of helping out your fellow man - becauase I'm sure there's a ton more GOOD stories as well. But in this case, the local authorities should be doing something.
It's a dangerous prospect these days, you can't trust anyone to be honest or have integrity.