Republican Texas Gov. Greg Abbott said Wednesday that in response to the San Antonio trailer tragedy, state troopers would set up additional truck checkpoints on highways.

He did not say how many checkpoints would be established or how many trucks would be stopped.

A tractor-trailer was found abandoned Monday with 67 people packed inside under the sweltering Texas sun.

The driver along with two other men from Mexico remained in custody Wednesday as the investigation continued into the tragedy that killed 53 people — the nation’s deadliest smuggling episode on the U.S.-Mexico border.

In April, Abbott gridlocked the 1,200-mile Texas border for a week by requiring every truck entering the state to underdo additional inspections as part of his ongoing fight with the Biden administration over immigration policy. He ultimately lifted the inspections after intensifying backlash and deepening economic losses.

While it’s not clear when or where the migrants boarded the truck bound for San Antonio, Homeland Security investigators believe it was on U.S. soil, near or in Laredo, Texas, U.S. Rep. Henry Cuellar told The Associated Press.

The truck went through a Border Patrol checkpoint northeast of Laredo on Interstate 35 on Monday, Cuellar and Mexican officials confirmed. It was registered in Alamo, Texas, but had fake plates and logos.

Officials in Mexico also released a surveillance photo showing the driver smiling at the checkpoint during the more than two-hour trip to San Antonio.