GM CEO Mary Barra will take "significant actions" that include holding specific employees accountable for the ignition switch defect that has plunged the automaker into a crisis.
"Mary will not be holding back and will be extremely candid" sources familiar with the investigation and its conclusions told CNBC.
Thursday morning Barra is expected to outline a number of steps the company has taken or will take as a result of an internal investigation conducted by former U.S. Attorney Anton Valukas.
Sources would not comment on whether those steps include firing employees linked to the defective ignition switch and GM's failure to notify the public and federal investigators about the flawed part. The Wall Street Journal, citing people familiar with the matter, said Valukas' report is not expected to blame Barra or senior management. Instead it will focus on problems with the carmaker's culture.
GM is expected to announce the dismissal of "a number of people," including the engineer who designed the ignition switch, Raymond DeGiorgio, and some members of the company's legal department, the newspaper said.
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Those familiar with internal probe say Barra will "not be holding back or glossing over of the facts about what went wrong."
General Motors said 13 deaths and 47 accidents have been linked to 2.6 million models recalled because of defective ignition switches.
A key part of the investigation into why GM failed to act sooner is whether or not the way in which the automaker is structured contributed to its slow action on safety issues.
Barra is expected to outline steps to make identifying safety issues a top priority for GM.
Her approach has been characterized as "bold and decisive."
Shortly before Barra releases the findings of the internal investigation to GM employees she and other top General Motors executives will brief key members of Congress and with the National Highway Traffic Administration.
Two committees on Capitol Hill and NHTSA have conducted their own investigations into the GM ignition switch recall.
Barra promised to keep key players in Washington appraised of the results of the three-month probe.
Despite a steady flow of damaging headlines and the recall of over 15 million vehicles worldwide, General Motors has weathered the bad news better than many expected.
Earlier this week, GM announced May sales in the United States climbed 12.6 percent, almost double the growth analysts were forecasting for the month.