The 18-wheeler used in a human-smuggling attempt that left 53 people dead inside its sweltering trailer traveled through an inland U.S. Border Patrol checkpoint with 73 migrants inside, The Associated Press and KHOU report.
A U.S official, speaking on condition of anonymity, said it wasn't immediately clear whether the vehicle was stopped or passed unimpeded through the checkpoint on Interstate 35, 26 miles northeast of the border city of Laredo, Texas.
Four suspects have been arrested in connection with the tragedy, including the alleged driver of the truck, Homero Zamorano Jr. The Justice Department said Zamorano, 45, was found in a field near the truck, pretending to be one of the smuggled migrants who survived.