Andres was one of at least five so-called "blind mules" identified in that 20-page federal complaint who were used by cartels to traffic drugs.

Others include a fourth-grade teacher and a sports medicine doctor. The blind mules had a few things in common: The bags were all secured the same way, each contained roughly the same amount of marijuana, and most of those caught drove a Ford. (The key code sources needed to create duplicate keys were much easier to access for Fords than for other types of vehicles, according to the complaint.)

FBI Special Agent Michael Martinez says the cartels' cunning didn't completely surprise him.

"We haven't been made aware of anything like this [before]," he said. "[The cartels] are getting very creative, this was something relatively new."

The investigation is ongoing, and Jesus Chavez's alleged co-conspirator, Carlos Gomez, remains a fugitive. Efforts to reach a lawyer for Chavez, who's in federal custody, were unsuccessful.

Despite the extensive vetting and background checks, sometimes those with criminal intent get by. U.S. Customs and Border Protection officials reported last week that a 30-year-old U.S. citizen and SENTRI pass holder allegedly attempted to cross the border from Tijuana, Mexico into southern California with nearly 54 pounds of methamphetamine in his car.

Despite being a free man with a cleared name, Juan Andres is still haunted by his experience.

"Being at school was really, really strange again. Seeing my friends who were taking class with me, and now they were ahead, was hard," he says.

Not knowing if he was still being spied on weighed on him: "I was afraid for the first day of school, afraid of leaving the parking garage."

And while six months of incarceration have affected the jazz lover's level of saxophone playing, he doesn't hold a grudge.

"I think the very important thing is we didn't hold resentment or anger or anything like that. It wasn't my fault; there was no way I could've avoided that. We take it like, 'things happen.' "