Why did Earl return to the scene of the crime?
When Bobby Earl loses Armstrong in the car chase at the end he returns to the cabin near where he murdered the little girl. Why go there when you know Armstrong will look for you there?
Didn't he want to get revenge to Mrs Armstrong (and her daughter as punishment)? He really had no problem with Armstrong and he just used him to secure this release. Why not take them to another secret spot where no-one will find you?