Since his arrest, Joel Luna has been a black eye for the U.S. Border Patrol — an agent accused of conspiring with Mexican drug cartels, who was connected with the gruesome beheading of a would-be snitch.

A jury in Brownsville found Luna guilty Tuesday of two counts of engaging in organized criminal activity, but they acquitted him of the murder of Jose Francisco Palacios Paz, according to the Associated Press.

Prosecutors argued that Luna used his position to help cartels send illegal weapons to Mexico and ship drugs north. He was sentenced to 20 years in prison. In return, he agreed not to appeal the case.

Palacios Paz, who friends called “Frankie,” worked at Veteran’s Tire Shop in Edinburg, Tex. In March 2015, cartel associates believe, he was on the verge of informing on a drug-trafficking operation that used the repair shop as a front, according to a Texas Tribune series.

As Jay Root and Neena Satija wrote, the case had “the familiar markings of mafia muscle and hardball tactics experts have come to associate with 21st-century cartel warfare — complete with a severed head supposedly secreted off to Mexico to prove a snitch was dead.”

Authorities fished his headless body out of Laguna Madre, a long, shallow body of water on the western coast of the Gulf of Mexico.

One of Luna’s brothers fired the fatal shot, according to testimony, but Luna’s involvement attracted the most headlines. He was an Iraq War veteran who had worked at Border Patrol for six years; he was supposed to protect people from grisly cartel violence, not participate in it.

His two brothers — Eduardo and Fernando — and two other men who worked at the tire shop were all charged. Luna’s attorney argued successfully that the former Border Patrol agent wasn’t at the tire shop on the day of the murder. He was working at a border checkpoint in Hebbronville, according to the San Antonio Express-News.

Eduardo Luna, who was tried at the same time as Joel Luna, was found guilty on all the counts he was charged with, including capital murder for retaliation, and sentenced to life in prison without parole, the AP reported.

Fernando, the oldest brother, testified against his now-estranged siblings, according to the Express-News.

After a flurry of conversations and text messages about the alleged snitching, Eduardo walked into the shop and shot Palacios in the head, according to the newspaper.

The case exposed the inner workings of Mexican drug cartels and highlighted the Luna family’s ties to one operation. The drug money ultimately ensnared Luna, who had seemingly made all the right choices through high school.

Joel Luna had joined the Army right out of high school, the Tribune reported, and took a job with the Border Patrol after being honorably discharged. Through it all, he was loyal to his family, caring for his father until the older man’s death in 2011.

But Eduardo Luna took a different path. He was referred to as a Gulf Cartel commander and associated with narcotics trafficker Mario Alberto Peña. The Lunas fled to Brownsville after a threat was made against the family.

At first, Joel Luna’s brothers lived with him. Then they moved to houses of their own nearby. Shortly afterward, they opened the tire shop.

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