to him through the fence. along this wall, there are more than 5,000 border patrol agents. but where there aren t, some have decided to take the law into their own hands. tim foley calls himself a certified tracker. he s the founder of the arizona border recon, a group of volunteers from all over the country. where are the cameras that you re using? they re hidden. reporter: dressed in camouflage and armed with his pistol, foley goes out to patrol this patch of the border, placing hidden cameras and looking for any signs of what he calls criminal activity. a lot of people might say you guys are a bunch of racists who just want to hunt down mexican people or people trying to cross the border. what do you say? well, that s because they have a preconceived notion of who we are, and of anybody who s trying to protect the border. they call them racists. you got the second-largest make-up of our group are