The current and first criminal charge against Brian Laundrie,
the
unauthorized use of a charge card for over $1,000,
makes this case a
Federal case, so that has lots of effects on how it will be handled, overall.
(And the card is possibly Gabby's, that she likely could not have authorized at the time he used it

)
In addition, Brian's parents, who have been heavily involved it appears, could be called by a Grand Jury now,
and there is no parent-child privilege, so their noncompliance might put them in contempt or obstruction of justice.....
so each step moves toward increasing the scope of info available.
I do not know which questions they would be required to answer, but if they paid for or provided transportation and supplies, once they knew there was a crime....that could be significant, too. (And could pressure them to reveal more info)