Four illegal immigrants were found in the back of a Wal-Mart truck, and the driver and two alleged accomplices were accused of trying to smuggle them through a Border Patrol checkpoint.

Authorities acting on a tip arrested driver Alejandro Hernandez and two other suspects Thursday just south of a checkpoint at Falfurrias, authorities said. The four Mexican nationals in the trailer were also taken into custody.

Documents filed in federal court Monday allege that Hernandez, 50, unloaded a delivery at a Wal-Mart in McAllen, then stopped at a truck stop in nearby Edinburg where he picked up the four immigrants.

Authorities said Leonor Gomez, 29, and her mother, Santos Gomez Moreno, had brought the immigrants to that meeting point in their van.

The two women followed the Wal-Mart truck north, planning to transfer the immigrants back to the van after they all cleared the Border Patrol checkpoint, authorities said in court documents. The Falfurrias checkpoint is about an hour north of the border.

Wal-Mart assisted the U.S. Immigration and Customs Enforcement agents in identifying Hernandez's truck after federal authorities were tipped to his activities.

Investigators said they believe Hernandez had used his truck to smuggle illegal immigrants through the checkpoint at least a half-dozen times.

"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." He said Hernandez had been suspended without pay.

Hernandez's attorney told The Monitor he had not yet had a chance to meet with his client.