Best to not jump to hasty conclusions based on what you read in the mainstream media. In SAR cases, the media gets things wrong at least as often as they get things right. (And that is being rather optimistic!)

One of the hallmarks of a well run search is that investigation by law enforcement begins immediatly and runs simultaneously with the field search. It is a very good bet that by now the authorities have determined if the text message came from the cell phone found in the cab, or from another phone (and if so which other phone). They will also be using whatever info can be extracted from the text ping to narrow down (or expand) the initial search area. The have also likely started to discreetly do background checks (criminal, financial, etc) on both the father and mother.

If this search is being run properly, and they are still treating it as a wilderness search (rather than a law enforcement problem), then we can assume they have at least some reason to do so. That's not to say that "something fishy" may not have occured, but it is way too early to jump to conclusions based on what little info has filtered through the press. The latest report I could find with google says they plan to continue ground searches tomorrow.