to explain why the couple was targeted. former intelligence official fred burton has been studying a turf war in mexico between two drug cartels, a former band of military guards called the zetas and the more traditional coast cartel. >> what most people don't realize when you're looking at the border is that there are certain portions that are not controlled by the mexican government. in the area of falcon lake, it was directly controlled by the zetas. and this was a very strong smuggling corridor for them. >> so you believe this was mistaken identity? >> clearly, all evidence indicates this was a case of mistaken identity based on the tactical intelligence i have seen surrounding the case. >> the most likely scenario is david and tiffany hartley had