General Motors Co said it has extended the tenure of its top lawyer, whose department was criticized over how it handled the issue of the automaker's defective ignition switch linked to more than 50 deaths, and the search for a replacement is ongoing, reported Reuters.

Michael Millikin, 66, will now retire in July and be "available for consulting services" through the end of the year, according to a footnote in the Detroit company's quarterly financial report filed last week with the U.S. Securities and Exchange Commission.

Last October, GM said Millikin would retire early in 2015 but remain general counsel, a position he has held since 2009, until a successor was named.

GM spokesman Jim Cain said on Monday that "the search is in great shape," but declined to provide further details on when a replacement would be named.

The No. 1 U.S. automaker last year faced criticism for waiting 11 years to recall millions of cars with ignition-switch problems that were linked to fatalities. The switch can slip out of position, stalling the vehicle and disabling air bags, and the defect led to the recall of 2.6 million vehicles.

The company is being investigated by state and federal prosecutors for issues related to the faulty switch.

GM said in October that Millikin was not forced out and had even been asked by Chief Executive Mary Barra to stay on longer.

As part of their attempt to build a case against GM, sources said last summer that U.S. federal prosecutors were looking at whether lawyers who attended key meetings about the switch problems acted appropriately after the meetings or whether they mishandled information discussed.

Millikin's legal department was heavily criticized in a 325-page report released by GM last June. Many of the 15 people fired or forced out from the department were attorneys or had worked under Millikin. However, the report said Millikin did not know the details of the ignition switch problem until early last year.

When Barra and Millikin were questioned at a U.S. Senate hearing last July, lawmakers demanded to know why Millikin was not fired. Barra defended Millikin at the time as "a man of incredible high integrity."