GM has brought in an outside law firm, Jenner & Block, to investigate why the maker didn't issue a recall of vehicles like the 2007 Chevy HHR that had a faulty ignition switch.

General Motors took steps today to get to the bottom of the ignition switch recall by hiring an outside law firm, Chicago-based Jenner & Block, with a reputation for getting answers.

The firm’s chairman, Anton “Tony” Valukas, is working together with GM’s general counsel, Michael Millikin, to conduct an investigation into the recall. Valukas is best known as the lawyer to investigated Lehman Brothers after it collapsed in 2008.

Valukas is a former U.S. attorney. It was his 2,200-page report outlining the causes of Lehman’s collapse that gained him notoriety. The report show that the firm had used a variety of accounting gimmicks to improve its balance sheet before it finally succumbed and filed bankruptcy.

He also previously investigated GM as lead counsel for the U.S. Securities and Exchange Commission’s four-year probing of “old” GM’s pension accounting. The probe ended without any charges being filed.

The goal of GM’s internal investigation is to determine why the maker didn’t institute a recall much sooner. The National Highway Traffic Safety Administration (NHTSA) is also conducting an investigation.

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Last week, NHTSA sent GM a 27-page document filled with a variety of questions and demanding detailed answers. In all, it was 107 questions and it’s due back to the agency by April 3. GM said it was already working on the queries.

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The agency could fine GM as much as $35 million and seek criminal charges if it decides the maker didn’t recall the affected vehicles when it new they were defective. The fine, if levied, would be the highest ever for an automaker.

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In addition, the Atlanta-based firm King & Spalding is also part of the team investigating the recall, according to a Reuters report. The firm represented “new” GM during some of its 2009 bankruptcy proceedings.

GM’s CEO Mary Barra said the company would “go above and beyond” in its handling of the recall of the 1.6 million vehicles. She told employees in an email that was later released to the media that GM’s would be judged not by the faulty ignitions, but it’s reaction to the recall.