I'm a little late on this one, but I hope it's okay for me to throw in my two bits on it.
This is a very interesting discussion and a lot of good points have been made. It's true that we don't know all the details and therefore shouldn't judge, but I agree with Nate on the principle of the thing. I won't reiterate something that's already been said, but one thing did occur to me while I was reading all this: cowardice.
Warrior 4 Jesus wrote:The least the people who witnessed it could do is find out from the dad and his daughter what the deal was.
Bingo. You may very well be genuinely concerned and trying to do the right thing (and as Tsukuyomi said, it's hard to know when you should step in), but the bottom line is, it's a lot easier to call the cops on someone than to approach them yourself and try to find out what's going on. I can understand you might be worried that a person is dangerous and wary for your own safety, but if you're more concerned for your own life than the life of the child in question, you have no business thinking you're so noble. Now, I'm not saying this applies to every situation. I'm not saying you should go up to someone in a ski mask holding a large sack and ask him if it's full of stolen money-- chances are he'd pull out a gun and shoot you on the spot-- but in a situation like this where you could do grievous damage to a family if you're wrong, you have to be willing to muster some of your own guts before bringing the authorities into it. Otherwise, you're a hypocrite.