SAN ANTONIO -- Federal investigators say the Zetas drug cartel is behind a massive human smuggling ring that operates through the Alamo City.
"We've seen a lot of people lose their lives in south Texas," said Jerry Robinette of the U.S. Dept. of Homeland Security.
After a year long investigation, federal agents arrested more than 30 people suspected of smuggling people across U.S. borders.
"It's well known that the Zetas are not just doing drugs but they're also in the business of smuggling people because that's turned into a really big cash cow for them," said immigration lawyer Rudy Castillo.
Castillo said he has worked many immigration cases in which the victims are help captive and terrorized until their relatives in America pay thousands of more dollars.
"They want the money," Castillo said.
Investigators believe the Zetas cartel may have a deeper connection. The names of the suspects were listed in an indictment. They were known to keep dozens of illegal immigrants in stash houses or apartments across San Antonio.
According to the affidavit, Fernando Martinez-Magana, also known as "Zeta 16," is listed as the ring leader. Federal agents are working closely with Mexican authorities to bring him down.