Four months ago, San Antonio police found a hot trailer truck at a Wal-Mart with 10 dead immigrants inside. It was one of the deadliest recent incidents of human smuggling.

Border law enforcement launched Operation Big Rig this week, asking for the public’s help to stop the crime and save lives.

Roy Cabrera has heard many human smuggling stories during his five years as a cargo truck driver.

“People hop in the back, hop in your trailers, open trailers, sneak in there, and they take the chance to get in the other side of the checkpoint," he explained.

Illegal human stowaways and hidden contraband are realities for many unsuspecting truck drivers along the U.S.-Mexico border, although Cabrera said that he’s never experienced it himself.

“They’ll put drugs up on the top,” he said pointing to his trailer. “You could easily get a couple of bundles, throw them in there, toss them in there. People will hide in there.”

Smugglers will use tight spaces to hide undocumented immigrants and drugs in places like air dams, the sleeper area, even the undercarriage, often avoiding the detection of lawful truck drivers who have no idea they’re carrying undocumented people or illegal products.

“Pretty much anywhere they can just stuff anything,” Cabrera noted.

However, most smuggling cases involve drivers who know they’re breaking federal law.

Whether the driver knows or not, human smuggling inside 18-wheelers is on the rise, according to the U.S. Border Patrol.

“We are experiencing a spike if we compare 2017 with 2016,” said Manuel Padilla, RGV sector chief for the Border Patrol.

Agents reported 45 cases in the Rio Grande Valley this year alone. That’s why Border Patrol and other South Texas officers launched Operation Big Rig on Friday, to raise awareness and enlist the eyes of the public.

“Every time we keep evolving our enforcement strategy, the criminal organizations keep adapting to what we’re doing,” Padilla explained.

Law enforcement knows it can’t fully screen every single truck that crosses the checkpoint, so they've made a renewed call to the public for help.

Agents hope that the campaign will create awareness and encourage citizens to report suspicious activity while warning smugglers, immigrants, and even truck drivers of the dangerous consequences of this crime.