"Man is known by the company he keeps and how well he keeps it". It is very hard to ignore the meth aspect of this family and the likelihood that it may have had something to do with the girls.
LE is clearly looking at the family and their associates. If we look at the recent arrests, the comments made about and by Lyric's parents, the situation with the uncle etc...the common denominator is drugs.
LE has not given the public any real reason to suspect that the abduction is in anyway random and related to the other abduction attempts, they would have a different focus IMO.