I'm coming out of lurk mode for this.
This case reeks of a perp who pre-planned this assault. Just as a burglar cases his place to rob, the person they are looking for cased this child. He knew her path to school, probably knew her mothers work schedule and knew the father wasn't in the home. That doesn't mean he knew the family personally - just that he is close by. Surely they are concentrating on the path to the park. They also need to question or requestion the other children (and their families) who meet up at the park and walk to school together.
Friday abduction - makes me think of Dave Westerfield, taking Danielle Van Dam. The weekened to do their deviant act, then worry about getting rid of the body. Time of abduction indicates, this person works a 2nd or 3rd shift, has Friday's off, or took the day off, may be unemployed or even retired.
Body not intact - indicates others live close enough around him, that he wouldn't risk moving her whole.
The whole thing is heartbreaking.