SAN ANTONIO - Closing arguments are set to begin Tuesday in the gruesome case against an accused cartel boss.
The trial against Marciano Vasquez is giving us a revealing look inside the cartel's inner workings.
News 4's Andrew Lofholm shows you how American teens get involved with the dangerous Mexican drug cartels.
Over the last two days, 21-year-old Eagle Pass native Saul Fernandez took the stand in federal court where cameras aren't allowed.
He testified that Zeta members would recruit teens, Fernandez was only 13 at the time, to work as scouts looking for border patrol agents.
Jerry Robinette, the former special agent in charge for ICE in San Antonio, says teens are ideal besides they're harder to prosecute if caught.
Fernandez also recruited classmates from his Eagle Pass high school to work as scouts and drivers. Drivers would make around $150 per bag, which was 60 pounds of marijuana, to transport.
At 15, he was caught by state authorities and taken into custody. A month later, he was let out, and fled to nearby Piedras Negras in Mexico with his pregnant girlfriend. There, he continued to transport for Zetas. Fernandez coordinated drug movement on the Mexico side.
After the marijuana was packed into bricks, they were moved to the U.S./Mexico border and given to mules.
Mules had two jobs, get the drugs across the Rio Grande River into America. Often times, using the marijuana taped to their bodies to float. On the way back to Mexico, they would bring guns and ammunition at the request of defendant Marciano Milan Vasquez, according to testimony. The AK-47's and AR-15's so heavy, the mules needed inner tubes to stay afloat.
Once the drugs made it to America, a driver would take the loot to another location before a stash house operator would take it from there. Only select few know where the stash houses are.
Closing statements are set for Tuesday. If convicted, Vasquez will be sentenced to life in prison.