NOGALES, AZ-- It's only been six months but border patrol agents have already seized more heroin than all of last year. Drug cartels are trying every tactic to bring more heroin to the U.S.

"They're always ahead of us. They're always looking, they're very innovative," Nogales Assistant Port Director Joe Agosttini said.

Those who carry heroin across the border are called "mules" and have found new ways to smuggle the drug.

"Now we're catching people that are 82 years old. Here it is, grandma coming through the port of entry," Agosttini said.

Mules are using children and the elderly, hiding heroin in family minivans and commercial trucks to avoid inspections.

"The gas tank is a very common compartment that they use to bring in narcotics. It's becoming a little bit more sophisticated," Agosttini said.

Lieutenant Matthew Thomas works for the Pinel County Sheriff's Department and has personally witnessed the increase in heroin.

"A couple years back, if you would find a pound of heroin, that would be a big load," Thomas said. "Nowadays, it's common to intercept 50 or 60 pounds, up to a hundred pounds of heroin.

Once the mules cross the border, they hide in the desert just off the interstate waiting for their rides.

Using the hillside as cover, the mules transport the drugs across the nation.

Metro Phoenix is a major distribution hub for heroin. Within three days, heroin is moved to cities like Chicago, Atlanta, New York City, and even Dayton, Ohio. Within hours, heroin is on the streets of Cleveland.