Does anyone know anything about the "babysitter"?
I suppose its possible that J may have seen/heard something going on between the step-father and the babysitter...Something that he would definitely tell his mother about. Something that the step-father and/or the babysitter wouldn't want him to tell his mother.
That could explain the fishy and confusing accounts of when J was last seen, by whom, where, and what he as doing....
I don't recall seeing any interviews with the sitter?
Also - its possible that J may have seen/heard someone visiting the step-father's or babysitter's apartment to sell them some drugs....Jonathan is old enough to know that, and repeat it.
He may have attempted to call his mother (as she may have instructed him to do) if he saw anything sketchy...especially if she was, perhaps, cleaning herself up and didn't want that crap in her apartment.