he keeps saying there's drugs, they're pouring in, they're pouring in. so dr. sanjay gupta went to the border to investigate. >> reporter: what you're witnessing here refrigerates to stop drugs from coming across the u.s./mexican border. >> almost every car crossing is crossing for a legitimate reason. it's a very small percentage that comes in carrying contraband, but i think when the inspectors pick up on something, their success rate is pretty high. when he saw the dog sit down at the back of the car, that's how that dog alerts. >> reporter: special agent in charge scott brown oversees the phoenix field office for homeland security investigations and drugs are a big part of what he does. this is how it happens. i mean, what we're witnessing here is -- >> is what happens every day along the southwest border of the u.s. and, you know, the officers at the ports of entry are phenomenal. they're fantastic at identifying