General Motors CEO Mary Barra will be back in the crosshairs this week as she faces more questioning from lawmakers about GM's fatal ignition switch debacle.

The hearings this week could be the last for Barra but may also be the hardest yet, the Wall Street Journal reported. Following a recall of 2.6 million small cars earlier this year, GM has been under investigation from federal regulators and the Justice Department for ignition switches that have been related to at least 54 crashes and 13 deaths.

Barra, who rose to head GM in January, has faced intense questioning in congressional hearings related to mounting evidence that the automaker was aware of ignition switch problems around a decade ago.

In her second appearance before a Senate subcommittee, Barra "will face Sen. Richard Blumenthal (D., Conn.), one of her harshest critics, and Sen. Claire McCaskill (D., Mo.), who remains skeptical of GM's response to the issue and its internal probe that cleared the automaker's executive team and pinned the lack of response on lower-level engineers, lawyers and a dysfunctional company culture," WSJ reported.

After the switch problem came to light, GM recalled millions of small cars, including the Chevrolet Cobalt and Saturn Ion models, and went on to issue separate calls for various repairs on more than 25 million vehicles altogether.

Barra has fired 15 employees, one of whom was former GM engineer Ray DeGiorgio, who has been closely linked to the problematic ignition switches. She additionally restructured the company by hiring more safety investigators and splitting GM's engineering division into two organizations.

GM has tapped high-profile attorney Kenneth Feinberg, who has worked on cases including 9/11 and the Virginia Tech shootings, to handle compensation for those injured and the families of those killed in GM vehicles. 

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