"The Dallas County grand jury did decline to indict Juan Robles Gutierrez after hearing all the evidence," Rachel Horton, a spokeswoman for the district attorney, told AFP.

Witnesses had initially reported that Robles, 37, risked his own life to pull several elderly passengers to safety after a fire started in the bus, causing a number of oxygen tanks onboard to explode.

But after interviewing hundreds of witnesses, state and federal officials said they could not find one person to confirm the report.

Robles was arrested shortly after the September 23 fire for being in the country illegally. He was charged with 23 counts of criminal negligence causing death on October 17.

Faulty brakes and insufficient maintenance have been cited as the most probably cause of the fire which heightened tensions during a massive evacuation ahead of the storm.

The bus company, which has a history of maintenance problems, was shut down in October but has not been charged in the fire. A federal grand jury investigation has been opened in Houston.

More than 2.5 million Texans took to the roadways in late September after the Houston mayor and several surrounding municipalities ordered a mandatory evacuation ahead of the powerful hurricane. Residents complained that journeys which usually took three or four hours ended up taking up to 36 hours as area highways turned into parking lots.

A traffic jam stretched at one point for nearly 30 kilometers (20 miles) on the I-45 highway behind the stricken bus, which was reduced to a charred hulk by the intense fire.

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