A woman who rode in the cab with Tyrone Williams as he was said to be smuggling illegal immigrants into the U.S. broke down in tears on the witness stand Friday in Houston, TX.

The Associated Press reports that Fatima Holloway testified she asked Williams to let the people out of the trailer after they began pounding on the walls. But, according to Holloway, Williams simply kept driving.

Nineteen immigrants died from heat or suffocation in the 2003 smuggling operation.

If convicted, Williams could face a possible death sentence.