I keep looking at the pictures of the garage and think maybe the perp was hiding there to rob the house and when he saw the family leave for the game, he thought no one was home. I would bet they left the door unlocked from the garage to the house. The garage does not look like where they parked their vehicle because there seems to be a boat or some other vehicle that's been parked there for some time.
Is it possible the perp was after money or something on people that may have lived in the house prior? How long did the family live there? Did they have a dog? Without knowing where Leila was found inside the house, it's hard to say if he went to her room for example to target her or if he encountered her for example in the kitchen, not expecting anyone home.
Looking at the location, and hearing the neighbors account, it seems the perp would have ran into the woods from the garage side of the house. Hopefully the dogs will pick up a trail. I can't see the getaway car theory, it would be very noticeable on that road. He's from the area and knows where to go from the other side, IMO.
So much we don't know.