A survivor of the nation's deadliest human smuggling attempt testified Wednesday that he and other illegal immigrants did everything they could to signal for help as they began succumbing to the heat in a sweltering tractor-trailer.

Matias Rafael Medina Flores, testifying in Spanish through an interpreter, said he used a mobile phone to call 911 twice from the truck, which contained more than 70 illegal immigrants. The first call was answered in English. A Spanish-speaking dispatcher picked up the second time, but no help arrived.

He and his companions shouted and banged against the trailer's walls and punched out one of the vehicle's signal lights, but Medina said the driver, Tyrone Williams (search), ignored them. He described the suffering of a 5-year-old boy, who eventually suffocated.

"The child was crying. He was crying so loud that he was making us feel what he felt," said Medina, who is from Honduras.

Defense attorney Craig Washington questioned whether Williams could have heard their screams. He has said Williams tried to help the immigrants by giving them water but couldn't understand their pleas because he doesn't speak Spanish.

The smuggling attempt resulted in the deaths of 19 illegal immigrants in May 2003. The tractor-trailer was discovered at a truck stop in Victoria, about 100 miles southwest of Houston. Seventeen people died inside the trailer and two others died later.

Williams, 34, a Jamaican citizen who lived in Schenectady, N.Y., is the only one of 14 defendants who could be sentenced to death if convicted.

Prosecutors said Williams faces the death penalty because he was the only one who could have saved the immigrants but instead ignored their cries for help.

Williams' lawyers have said their client faces capital punishment because he is black. Washington appealed the race issue to the U.S. Supreme Court (search), which refused Monday to hear the case.

Federal law allows the death penalty in fatal smuggling cases. Williams was indicted on 58 counts of harboring and transporting illegal immigrants.