McALLEN, Texas -- A Wal-Mart truck driver and two women were arrested, accused of attempting to smuggle illegal immigrants through a Border Patrol checkpoint in the rig’s trailer.

Alejandro Hernandez, 50, unloaded a delivery at a Wal-Mart in McAllen then stopped at an Edinburg truckstop. There Leonor Gomez, 29, and her mother Santos Gomez Moreno, transferred the immigrants from their van to Hernandez’s trailer, according documents filed in federal court Monday.

Wal-Mart assisted the U.S. Immigration and Customs Enforcement agents to identify Hernandez’s route and truck after federal authorities were tipped to his alleged activities.

“At Wal-Mart we expect our associates to conduct themselves in a lawful and ethical manner,” company spokesman Don Fogleman told The (McAllen) Monitor. “This situation is of deep concern.”

Investigators believe Hernandez had used his truck to smuggle illegal immigrants through the checkpoint, which is about an hour north of the border, at least a half-dozen times. Gomez and her mother followed Hernandez north in their van with the plan being to transfer the immigrants back to the van once it cleared the checkpoint, court documents show.

Agents arrested the trio just south of the checkpoint Thursday.  They stopped the truck before it reached the checkpoint because they were concerned about the well-being of the men in the trailer, according to the court documents.

All were taken into custody along with the four Mexican nationals in the trailer, which was empty except for some pallets.