WASHINGTON (Reuters) -- U.S. lawmakers investigating General Motors' slow recall of 2.6 million cars are zeroing in on engineers and others who may have been aware of problems with ignition switches linked to at least 13 deaths.
One month after congressional committees launched formal probes into why it took GM more than a decade to respond to ignition switch safety defects with the recall, lawmakers still do not know exactly how company engineers initially reacted to the problem or whether senior executives were made aware of it.
House of Representatives Energy and Commerce Committee investigators last month spoke with GM lawyers about company documents.
That panel and the Senate Commerce Science and Transportation Committee now want to hear from people with direct knowledge of the switch defect, which can unexpectedly shut off engines, disabling airbags and making steering and braking more difficult.
GM CEO Mary Barra had few detailed answers for lawmakers at hearings last week.
"If you really want to get to the bottom of it you really have to talk to people who were actually there when all this was going on," said U.S. Sen. John Thune of South Dakota, the senior Republican on the Senate committee.
Some members of Congress and their aides expressed interest in calling GM engineers, including ignition switch designer Ray DeGiorgio, to testify at hearings that will likely come this spring or summer.
Congressional investigators have documents from GM that help explain some decisions. One e-mail chain involved engineer John Hendler and Lori Queen, an executive who had responsibility for small car development, discussing costs of redesigning the switch, for instance. DeGiorgio, Hendler and Queen did not respond to Reuters' requests for comment.
GM documents already turned over to the House committee raise questions that aides say are still unanswered, including how GM changed the switch in 2006.
DeGiorgio testified last year in a deposition related to a suit against GM that he was unaware of a change in the part. But a document turned over to Congress showed that he approved redesigning the switch in 2006. The part number was not changed at the time, and the document also lacks a signature by a "GM Validation Engineer." Investigators want to know why.
U.S. Sen. Richard Blumenthal, a former federal prosecutor and Connecticut state attorney general, said he wants to question lead GM engineers, but also "lower-level officials who may have knowledge about the reasons GM not only failed to correct it (the ignition switch problem), but concealed it."
Republican U.S. Sen. Kelly Ayotte, a former New Hampshire state attorney general who serves on the Senate Commerce, Science and Transportation panel that grilled GM CEO Barra, has said GM's behavior may be criminal.
"The thing that I found most appalling is the deception here and that deception is really outrageous and totally unacceptable in terms of what they knew, when they knew it and what they told the public," Ayotte told Reuters.
Ayotte said she "very much" wants to get testimony from former federal prosecutor Anton Valukas, who was hired by GM to conduct an internal investigation of what has become a major safety issue, as well as a public-relations nightmare for the Detroit automaker.
Barra told Congress that she had to wait until Valukas's investigation finished to answer many questions. The probe should be completed by June, she said.
Asked about Ayotte's comments about "deception" in the company, GM spokesman Greg Martin on Wednesday said the automaker "is taking an unsparing look at the circumstances that led to this recall" and that as facts become available, "we will not wait to take action."
Martin said that GM will cooperate fully with Congress and an investigation by the National Highway Traffic Safety Administration, when asked about the possibility of Valukas testifying to lawmakers.
As Congress proceeds with its investigation, it also is laying the groundwork for possible legislation later this year that would prevent future safety defects from going unaddressed.
While it is not clear what kind of a measure would win Republican and Democratic support, key lawmakers already are weighing their options.
The House committee, which is still trying to "connect the dots," will "identify the problem and then come back with corrective legislation to fix it," pledged Chairman Fred Upton, R-Mich., in remarks to reporters on Tuesday.
Thune noted "the outrage" in Congress was bipartisan given the deaths linked to GM's defective cars. And so, he said, if it is determined that a legislative effort is needed, "I suspect it would be pretty bipartisan" too.
While he talked about a "legislative fix," Upton would not say whether it might aim to increase civil or criminal penalties on manufacturers or impose tougher accident reporting requirements on automakers.
Upton helped write a 2000 law that arose out of a congressional investigation into problems involving Firestone tires on Ford Explorers.
Democrats already have proposed legislation to increase the maximum civil penalties for violations of federal safety standards. They also would strengthen reporting requirements when there are fatalities and increase funding for agencies that oversee the auto industry.
Consumers would get broader access to documents collected by the government, under this plan.
If legislation is pursued, it could be slowed by long recesses planned by Congress this year as members focus more on campaigning for re-election in November.
Also, any legislative action is expected to prompt a spirited auto industry lobbying campaign to mold a bill to its liking.
Barra is also likely to be called back to Capitol Hill, to give lawmakers another chance to press her on steps she would take to prevent dangerous cars from remaining on the road.
In her testimony last week, Barra repeatedly apologized to Congress for the safety defect but provided few answers to Congress for why it was allowed to fester for so long amid repeated consumer complaints.
Barra, who became CEO in January after a 33-year GM career, said more will be known when the internal probe wraps up.
That did not please members of Congress.
"She could have gotten somebody who could have given her the information. But she thought she could just say, 'I'm sorry,' and that would be good enough" said U.S. Rep. Henry Waxman, D-Calif., the senior Democrat on the House Energy and Commerce Committee, in a brief interview.