I'm very diligent about keeping my daughter in my sight, not just know where she is - IN MY SIGHT. One of my fears though is that someone breaks into our house and kidnaps/rapes/kills her while I am asleep in the next room. That came true for another 11 year old girl in Olympia. A monster came into her house through an unlocked door, raped her, then left w/o anyone else in the house waking up.
What's the solution for this? Lock your doors, of course but that's no guarantee. Get a gun, sure - but if you don't wake up - you can't use it. Get an alarm installed - may be your best bet but it's not 100% - as it doesn't take long to grab a child and run. Get a loud dog that would bark and/or attack? That may be the 2nd best option in this scenario.
In this scenario the best option is to teach your child is to fight back. Scream. Yell FIRE at the top of your lungs. Wake me up so that I can put a bullet in this monster. Teach them to think and to take a breath when scared and to re-act.
Two books that should be mandatory reading:
The Gift of Fear
Protecting the Gift
Both are by Gavin de Becker and they are both EXCELLENT reading.
UPDATE: SUSPECT ARRESTED. Convict and then hang him.