I agree, it's baffling.
Back to the case. If Abby is being harbored or held by an adult, this person is likely still going to work during the day (assuming he or she has a job). I think this case will be solved by vigilance in the community (not necessarily the N. Conway community, as I believe she is no longer in her home town). Neighbors, a mailman, employers, friends or family members
I hope everyone in the Northeast has their eyes and ears open for strange behavior. Of course, no one ever thinks that someone they know could be involved in something like this...