A bus that crashed last year, killing 17 passengers, may be among hundreds of vehicles issued inspection stickers by a Houston shop that routinely gave passing grades to automobiles it never saw, authorities say.

On Monday, the Texas Department of Public Safety announced the arrest of Cesar Hernandez, 27, and two other men from 5-Minute Inspections on charges of tampering with a government document, a second-degree felony punishable by up to 20 years in prison.

Hernandez is listed on documents as having inspected a bus that crashed in Sherman on Aug. 8, 2008, as it carried 55 Vietnamese-American passengers from Houston to a Catholic retreat in Missouri.

Last month, the National Transportation Safety Board said that 5-Minute Inspections missed an unlawful tire retread and other problems with the bus during its inspection. The NTSB found that a puncture in the retread tire led to the crash, believed to be the worst of its kind in state history.

But DPS officials on Monday cast doubt on whether the bus was ever examined by 5-Minute Inspections technicians.

"There's a criminal investigation that is going on right now, and we're looking at a number of issues relating to this inspection company issuing certificates, hundreds a month, on vehicles that it did not actually inspect," said Tela Mange, a DPS spokeswoman.

"The fact that this is the company that performed the inspection on the bus that crashed in Sherman is additional food for thought," she said.

The NTSB says that based on its conversations with technicians at 5-Minute Inspections, it determined that the bus was visually checked about a week before the crash.

The technicians told the investigators that their inspection lasted about 45 minutes.

Federal authorities, though, say a proper analysis of a bus would have taken about twice as long. They also found that the shop was not equipped to get a good view of the bus' undercarriage, which would have been part of a thorough inspection.

Mange said DPS troopers uncovered information about three weeks ago that led them to question whether the Houston shop actually inspected the bus.

She would not reveal the nature of the information but hinted that it was more detailed than what federal authorities discovered.

"They're taking their word for it," Mange said Monday of NTSB investigators' conclusion that an inspection actually occurred. "We're going to look at that."

During a four-hour NTSB hearing in Washington on Oct. 27, federal investigators and witnesses railed about the work 5-Minute Inspections did on the bus.

There was no mention then that the company might not have actually performed the inspection.

Federal authorities also harshly criticized the DPS for a lack of oversight of the inspection and bus registration process.

In addition to Hernandez, the DPS also charged two other 5-Minute employees, Ernesto Bastard, 19; and Miguel Castillo, 49, with tampering with a government document.

Investigators believe that the bus driver, Barrett Broussard, had used cocaine and alcohol hours before starting the trip. However, Broussard apparently made no maneuvers that caused the crash, federal investigators found.

He has not been charged, and DPS said that their criminal investigation does not involve the driver, only the inspection shop.

Staff writer Todd Gillman contributed to this story.