A US Senator said General Motors' much-anticipated internal report on the circumstances that led to a deadly flaw going unfixed for more than a decade, amounts to a whitewashing of the problem.

Sen. Richard Blumenthal (D-Conn.), one of the most vocal critics of the company over its handling of an ignition-switch malfunction that has killed at least 13 motorists, said the internal report, compiled by former US Attorney Anton Valukas, failed to answer key questions and didn't identify how victims will be compensated.

The report, "amounts to circling the wagons to marshal a legal defense," Blumenthal said during a conference call with reporters. "It's the best report that money can buy. It absolves upper management and limits culpability. This report leaves really critical questions unanswered. It's a failure to come clean and acknowledge full responsibility."

Earlier Thursday, the National Highway Traffic Safety Administration released a partially redacted copy of the 325-page report, which found no evidence of a conspiracy to cover up the ignition-switch failure that GM had known about for at least 11 years before issuing a recall in February.

GM CEO Mary Barra (pictured above with Dan Ammann and Mark Reuss) had called the report an unflinching look at the company's shortcomings, which she found "extremely tough, brutally tough and deeply troubling."

But during a press conference held before the release of the report, members of her executive team wouldn't say the company would waive any protections offered by its 2009 bankruptcy to potential litigation – a key point in how the company might address financial responsibilities resulting from legal claims. Barra deferred answering many questions about the contents of the report to Valukas, and deferred questions about the compensation fund to Kenneth Feinberg, an independent consultant who will administer the claims. Neither Valukas nor Feinberg were available to answer questions.

Many questions remain unresolved.

Who qualifies as a victim? GM has acknowledged 13 deaths related to the defect, though many, including NHTSA administrator David Friedman expect that number to rise. The report does not offer details on who qualifies as a victim of the defect, and the company does not acknowledge many ongoing claims.

"Clearly, the number is more than 13," Blumenthal said. "As much as compensation is important, public acknowledgement of those victims is also critical."

Why did GM's engineers fail to establish a link between ignition-switches moving to the accessory position and airbag non-deployments that contributed to the fatalities?

Why were cars that suddenly shut off while driving treated as customer-convenience problems, and not safety hazards?

"You would think the investigation would help to shape the fund in determining how many victims there were, how many should be compensated and how many injuries and others who were harmed, but there are none of those relevant results from this investigation," Blumenthal said.

He said he would continue to press for federal legislation that would compel automakers to be more transparent when their cars have dangerous problems. If enacted, the law would require them to provide more information on fatal crashes to the Early Warning Reporting database, and it would also require NHTSA to upgrade its online databases to improve search capabilities.

Blumenthal has co-sponsored the pending legislation, the "Early Warning Reporting System Improvement Act of 2014," with Sen. Ed Markey (D-Mass.). On Thursday, Markey was critical of the Valukas report.

"We need more than an accounting of past mistakes," he said. "We need to ensure accountability and that permanent measures are put in place to prevent future deaths. An internal investigation alone is not nearly enough to ensure that a decade-long tragedy like this never happens again. Until we end the 'don't ask, don't tell' culture that enabled these tragedies, we risk the potential that auto manufacturers will again keep deadly secrets."

Blumenthal said he's still troubled that GM won't issue a directive that would implore drivers to park their cars until they're fixed. Currently, GM says it has made fixes to about 113,000 vehicles of the more than 2.5 million vehicles recalled because of the defective-ignition switches. The company says it is on track to have all the vehicles fixed by October.

He also said that if GM is intent on truly being accountable, it should ensure that legal records from lawsuits involving the defective switches are open to the public. Instead, he charged that GM has arranged confidential settlements with victims that seal records which could have otherwise helped warn the public about the safety hazards.

He said GM needs to stop shifting responsibility for answering questions to Feinberg and Valukas.

"Which is made all the more important by the incomplete nature of this report," Blumenthal said. "Clearly, this one is not independent or completely objective."

This article originally appeared on Autoblog.com