WASHINGTON—The federal investigation of a fatal Texas bus crash zeroed in Tuesday on foreign-made passenger buses that operate in the U.S. but don’t meet minimum U.S. safety standards.

Witness testimony revealed shortcomings in safety regulations and enforcement intended to ensure the buses are not used to carry passengers on U.S. roads.

Debbie Hersman, a National Transportation Safety Board member, said the regulations are a patchwork enforced by different agencies.

No motorcoaches are made in the U.S., Hersman said. She suggested companies purchase buses that don’t comply with federal standards because they are cheaper. The price for a bus that meets U.S. safety rules is about $425,000, compared to about $211,000 for the bus in the Texas crash, she said.

“We have no idea how many noncompliant buses are in the country,” said Hersman, who presided over the hearing, which continues Wednesday.

Forty-seven passengers were returning to Houston from Monterrey, Mexico, Jan. 2 aboard the 2005 Mexican-made Volvo bus. The driver veered off the road near Victoria, Texas, and overcorrected, causing the bus to flip on its side and strike a guardrail. Pablo Mendez was killed and his wife and daughter were injured along with dozens of other passengers.

Hersman described a convoluted route the bus owner took to exploit gaps in California vehicle registration laws and ultimately get Texas license plates. The bus could not be registered in Texas because it did not meet federal safety standards. With the help of Green River Buses, based in Dallas, the bus was registered in California using a Los Angeles address. Once registered in California it could be registered and operate in Texas.

Hersman said the owner “went to some pains” to register the bus in two states in an effort to “take advantage of loopholes in the registration process,” Hersman said.

Capricorn Bus Lines of Houston owned the bus and leased it to International Charter Services Inc., which leased it back to Capricorn. Capricorn then supplied drivers, maintenance and insurance. Capricorn did not have authority from the U.S. Transportation Department to operate, and instead used International’s DOT charter number, said NTSB investigator Pete Kotowski at the hearing.

The bus was cited in Oct. 2006 near Victoria, Texas, for not displaying Texas plates. It was registered in California in April 2007 under the International Registration Plan or IRP, which allows motorcoaches registered in one state to operate in another under IRP member jurisdiction. The bus was re-registered eight months later in Texas to operate as an intrastate carrier.