Washington – A General Motors-commissioned report on the company’s slow response to a deadly ignition-switch defect was blasted Thursday by Sen. Richard Blumenthal, D-Conn., who said it left critical questions unanswered and absolved top officials of responsibility.

“The report is not only a window into GM’s incompetence but also a failure to come clean and acknowledge full responsibility,” Blumenthal told reporters after reading the report written by a former U.S. attorney, Anton Valukas.

Blumenthal also said the ties between the Valukas’ law firm and GM “undermined the validity of the report.”

“The GM public relations campaign is pitching this report as an independent review. In truth, it seems like the best report money can buy,” Blumenthal said.

He also vowed to put more pressure on congressional investigators and the Justice Department to investigate GM more closely and he’s  considering legislation that would force GM to compensate victims more fully.

“The company has yet to set up an amount for the compensation fund or the criteria for it,” Blumenthal said.

Congressional critics like Blumenthal say the Valukas report left unanswered questions, including how many people have died as a result of the faulty ignition switch and why GM had minimized the importance of reports that vehicles like the Chevrolet Cobalt were stalling on the road.

Mary Barra, the chief executive officer of GM, said Thursday that she fired 15 people who “acted inappropriately” in the ignition switch scandal, but said there was “no conspiracy” at the company.