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 gulf 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. and the area of falcon lake was directly controlled by the zetas, and this was a very strong smuggling corridor for them. >> reporter: so you believe this was mistaken identity? >> clearly, all evidence indicates that this was a case of mistaken identity base on the tactical intelligence i've seen surrounding the case. >> the most likely scenario is, david and tiffany hartley had wandered into a drug war and were mistaken as the enemy. >> reporter: zapata county sheriff siggy gonzalez believes the hartleys not only wandered into a war but arrive on the mexican side of falcon lake at the exact moment a cartel was about to move a large amount of marijuana. up on a bluff, the spotters, his sources told him, caught the