when we rrive, lapre spots water bottles and what are known as "sneaky feet," carpet-soled shoes that don't leave footprints. >> so this tells me that these are, these guys might have been packindo because the blankets are all the same. so usually with immigrants that come across, you get personal items, clotving that's inual or unique to the individual. and here we have a groupf stuff that's uniform. >> reporter: it's all uniform, as if it were a standard issue. that's really interesting. >>thhe backpacks are all same. >> reporter: so you and your department, you're really the last line of defense. >> yes.>> eporter: so brazen are the mexican drug cartels, lapre says th even have their own religious shrine, right here in arizona. have you ever seen this lit up? >> yes, i have. quite a few times. it's either lit or not. depending on which one is, going on is depending if the smugglers know we're in the area or if we're not in the area. >> reporter: so they're sending a signal. this is a lighthouse effectively. >> e xactly. >> reporter: why don't you take it down? >> well number one it