K9s helping U.S. Customs and Border Protection, in their mission to protect U.S. against drugs

U.S. Customs and Border Protection has one main job: providing counter-terrorism. That is followed by the daunting task of keeping drugs from being brought across the United States - Mexico border.

It's a responsibility officers say grows increasingly difficult on a daily basis, as the illegal drug epidemic surges, but dogs are being trained to stay one step ahead of drug cartels.

For Customs K9 officer Carlos Maytorena, Rocky is his partner. The team is responsible for the detection and seizure of illegal narcotics.

"They can differentiate the odors from gas to plastic to duct tape, bondo, fresh paint," said Maytorea.

Officer Maytorea said Rocky alerted him to 40 lbs of meth, vacuum-sealed and stuffed into a gas tank a few weekends ago.

"He dove underneath the car," said Maytorea.

Last month, it was 720 grams of fentanyl, hidden in the center counsel under the gear shift.

"When I put him inside the vehicle, he gave me an indication of where it was at, and just stayed there," said Maytorea. "A solid stare towards the location of the narcotics."

The Port of Nogales is the largest port of entry in the State of Arizona, where thousands of personal vehicles and cargo shipments enter daily.

"First, it started with marijuana," said Marcia Armendariz. "Cocaine, heroine, meth, you know, started being very popular."

Supervisor Marcia Armendariz said on August 18, two Mexican nationals and two U.S. citizens were busted, while attempting to smuggle approximately $685,000 worth of cocaine and meth into the country. On August 21, at the DeConcini Crossing, a canine alerted officers to the dashboard of a vehicle, driven by a 63-year-old Mexican woman.

36 lbs of cocaine, worth more than $410,000, were found.

"The relationship between the K9 handler and the K9 is very important," said Armendariz. "It's very crucial, because that handler needs to know how to read its K9."

The K9, according to Armendariz, has to be keen to the latest drug trends, like fentanyl. The supervisor described it as the "new heroin".

"The drug cartels evolve with newer products, newer drugs," said Armendariz. "At the same time that they evolve, we have to evolve with them."

The K9 and handler train extensively, off-site, at least twice a month. However, it's what they do at the Port of Entry, every single day, that ensures they are prepared.

Everyday, everyday is a challenge," said Maytorea.

The challenge isn't finding the drugs, as much as it is identifying them. so the public becomes part of the solution.

"Say, for example, that white SUV coming this way, we let the public know, and we ask them if they are OK with us putting a training aid for the K9s," said Armendariz.

Officer Maytorena and Rocky have been working together since January. Like all the K9s used by U.S. Customs and Border Protection, the 7-year-old German Shepard is considered an essential tool, a key component at the border.