This kind of think really tears me up. I have two daughters and they're all I can think about when I read about this horrible act. I want to send them to self-defense classes and then lock them in their rooms.
I think we've become over-protective of our children in recent years. I have to consciously try to make myself let them do things that we never thought twice about when I was a kid - like walk to a friend's house a block away. I want them to develop a sense of independence and self-reliance, but stories like this - few as they are - make it harder for me to not smother them with "no, you can't do that".
Happiness will be a long time away from those families.