Cardona was also making a name for himself at that time, and impressing the same narco leaders.
If eyes are a window into the soul then unraveling the myth of Gabriel Cardona gets complicated. And like everything in the violent world of drug cartels, unraveling truth and myth seems fleeting.
On the surface, Gabriel Cardona's eyes belong to a baby face.
If you know nothing about him, it's hard to imagine he could have been a lethal assassin.
But then there are those eyes tattooed on his eyelids.
When you see those, they seem like the window into the cold, calculated soul that made Cardona a notoriously effective killer for the Zetas.
Cardona smiled when asked how many people he remembers killing for the Zetas.
"I have no idea," Cardona said. "It's a violent world."
After some prodding, Cardona estimates he probably killed close to 30 people in less than two years.
Cardona and Reta say they were paid thousands of dollars a week just to be available -- ready at all times to answer the call to kill.
When orders from cartel leaders came, the men would begin hunting their prey.
It's hard to pinpoint just how much money they were paid. Cardona claims he was spending more than $10,000 a week. The men say cartel leaders provided them with a house and extravagant cars. Cardona was often seen driving around town in a Mercedes.
For each ordered hit, they said, they were paid an extra fee -- about $10,000, and sometimes even more depending on the importance of the targeted victim.
The money and lifestyle were so seductive and intoxicating that both teenagers dropped out of school and started living the high-rolling, lavish lifestyle. Reta dropped out sixth grade; Cardona left school in ninth grade.
"It gives you that sense that you could do anything without being touched and having that sense of power," Cardona said. "You think that it's not going to end because it just keeps coming."
In interrogation videos made shortly after his arrest in 2009, Reta told a Laredo police detective how killing made him feel like "Superman."
The job of a cartel assassin isn't one most people grow old and retire from. They either end up in prison, or it's likely their tortured corpse will be left along a blood-soaked path to nowhere in the Mexican countryside.
Cardona and Reta didn't last long in that world. They each say they lived the life for about three years, Cardona from age 16 to 19; Reta, from age 13 to 16.
Eventually Laredo police detectives zeroed in on the teen assassins.
Cardona was arrested and pleaded guilty to killing seven men and to conspiracy to kidnap and kill in a foreign country. He was sentenced to more than 80 years in prison.
Reta said he began to fear that rival cartel members were getting close to killing him as retribution, so while working on an assignment in Monterrey, Mexico, he called a contact at the U.S. Drug Enforcement Agency and surrendered.
Reta pleaded guilty to two murders and was handed two prison sentences, of 30 and 40 years.
"I've come to regret everything I've done," Reta said. "I couldn't take it anymore. It was real hard for me. I wasn't living my life."
For his part, Cardona is not as remorseful. He doesn't spend a lot of time thinking about the violence he wielded, he said. His mind isn't haunted by violent images from his former life.
"I'm really a good person," he said. "It just happened."