I'm going to repost my post about why I don't think it's a robbery or the parents were the target for the night crew. JMO:
It's a very big jump for any criminal to go from burglary to double murder and kidnapping. Many people who are just fine with robbery or even harming an adult would not hurt a child. There's a reason why child predators are often killed or targeted in prison and it's because even other serious criminals believe that harming a child is wrong.
If you actually look at previous cases where a family is murdered and a young daughter is taken, it is often the work of a child sexual predator.
If the motive was robbery, or to "get back" at the parents for something, why would the perpetrator kidnap Jayme? If that was the point, why not murder all three people in their home? The parents are dead, so "taking" Jayme inflicts no further damage on them. Why would you want to be responsible for a living 13 year old who is just a walking evidence shedding machine if your goal has been accomplished by breaking into a home and killing the residents?
It doesn't make sense. It gives LE the greatest impetus possible to track you down on the hope that the child is still alive. It makes your escape so much more complicated and your continued running much more perilous than if you were alone and could slip away.
The only thing that makes sense is that Jayme was the purpose of this. I know people have asked why didn't the perpetrator snatch her off the street, but how do we know she was often alone outside or anywhere? If her parents were "reclusive" as early reports from the neighbors state, Jayme may have been too - keeping to herself or her very populated extracurricular activities that all seemed to be team sports (dance, cross country). Perhaps after watching her, the perpetrator knew the best chance he knew to find Jayme alone was at midnight at her house. If he was someone she spoke to online under false pretenses she may have said in casual conversation that her parents go to bed early, or she's often up late in her room reading. We just don't know.
But we do have the benefit of examining previous situations and cases that appeared similar on the outside, and LE, of course, has inside information to compare as well.