General Motors CEO Mary Barra "stonewalled" lawmakers when she testified on the automaker's massive recall of faulty ignition switches, a member of the House Energy and Commerce Committee told CNBC on Wednesday.
Rep. Diana DeGette, D-Colo., a ranking member on the congressional subcommittee investigating GM's response to the deadly problem, said Barra dodged basic questions on documents that the car company provided to Congress.
"So it was her own documents that she refused to acknowledge," DeGette said on CNBC's "Squawk Box." "I just hope that the investigation going forward has a different tone than the stonewalling we got yesterday."
In response to DeGette's comments, GM spokesman Greg Martin told CNBC that the company planned to cooperate with lawmakers but did not want to "sacrifice accuracy for speed."
"Right now we have an unsparing internal investigation underway," Martin said. "We're not at a point where we can release preliminary details. ... We will share findings with all parties as they become available."
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Barra appears before a Senate committee on Wednesday for another round of testimony. Lawmakers want to know why GM launched a recall of the faulty ignition switches this year when it had known of problems with the car parts since 2001.
The switches have been linked to at least 13 deaths, but DeGette suspects the number could rise.
"Was it willful?" DeGette asked. "Were they consciously not reporting this or was there just some massive lack of communication within the company?"
—By CNBC's Jeff Morganteen. The Associated Press and Reuters contributed to this report.