True, and I think we all know how this is likely to turn out. He not only came back without her, he was driving her van.
But as of this morning, the North Port police made it clear that this is still a missing person case and that Laundrie is not wanted for a crime.
Person of interest and suspect aren't the same thing. "Person of interest" has no legal meaning.
A formally named suspect can be taken into custody for questioning, but he still doesn't have to talk to police, and he has to be released if there's not enough evidence to charge him.