I've been looking through all the pictures of the house trying to figure out how & where an intruder could enter the home. IMO the windows are too far off the ground to enter a window without the aid of something to climb up on, so IMO if an intruder did enter it was through a door.
Then I did a little digging on the house itself.
It's only a 2 bedroom house, 881 square feet. Many moons ago when I was a young mother I lived in a 930 square foot 3 bedroom house and heard every little noise in that house. With that home being only 2 bedrooms, and mom & grandma living in the house... where was Tyler's crib? And why didn't anyone hear anything???
http://www.zillow.com/homedetails/7730-Clevedon-St-Saint-Louis-MO-63123/2832591_zpid/
It's the house with the squiggley walk-way. In news footage earlier the house with the red car in it towards the bottom of the photo is a neighbor who had a large dog, looked like a Boxer. The SWAT team with the K-9 team told him to put the dog inside when they were searching the area. Did that dog bark, if he was outside? The houses are so close together I hope someone saw something!