CBS Corp. has tapped Covington & Burling and Debevoise & Plimpton to conduct an investigation into allegations of sexual misconduct by CEO Leslie Moonves, naming two former prosecutors to lead the probe.

The move to have two separate firms collectively handle a high-profile investigation is unusual, but not unprecedented, attorneys said on Thursday.

In a statement issued late Wednesday night, the CBS board said Nancy Kestenbaum, the former chief of the General Crimes Unit in Manhattan, would lead the Covington investigation, and former U.S. Securities and Exchange Commission chair Mary Jo White would head the Debevoise effort.

Kestenbaum joined Covington in 2003, after working for nearly 10 years as a federal prosecutor in the U.S. Attorney's Office for the Southern District of New York. White, who chaired the SEC during the Obama administration from 2013 to 2017, was also the first woman to ever serve as U.S. attorney in the Southern District. She worked as a litigation partner on Debevoise' white-collar defense team from 1983 to 1990, before rejoining the firm last year.

Perhaps the most prominent example of a two-firm probe was Pepper Hamilton's work alongside former FBI director Louis Freeh's law firm, Freeh, Sporkin & Sullivan, in the investigation into Penn State's handling of the Jerry Sandusky sexual abuse scandal in 2012.

However, other joint investigations announced this year include Gibson, Dunn & Crutcher and Van Dermyden Maddux's work around allegations of sexual harassment levied against a California state senator, as well as the decision by the Dallas Mavericks to retain former New Jersey Attorney General Anne Milgram and longtime New York City prosecutor Evan Krutoy to conduct an internal investigation into allegations of sexual misconduct involving the team's longtime former president and CEO.

“It's unusual for an organization to hire two high-profile lawyers or law firms to handle an internal investigation,” said Sarah Duggin, professor at Catholic University's Columbus School of Law. “Sometimes organizations hire more than one firm because an investigation involves different kinds of allegations, diverse areas of law, distinct business operations, multiple locations, or an extraordinarily broad scope of work, but this is not the usual practice.”

Linda Dale Hoffa, a partner at Dilworth Paxson, said the decision could reflect the unique circumstances of the Moonves case, including the need for additional resources and varying areas of expertise.

“It seems to me that both Mary Jo White and Nancy Kestenbaum are very professional and well-respected attorneys,” she said. “Going into this, they've surely through thought and have an understanding of how this partnership would work. It's terrific that CBS is doing this, that they're retaining such top-flight attorneys, and that there are these terrific women in the white-collar defense bar.”

Covington and Debevoise are reviewing allegations, reported last week by The New Yorker, that Moonves had engaged in a pattern of abusive behavior for decades and used his position to threaten women who rejected his advances. Moonves has said that he regretted making women feel uncomfortable, but denied allegations of abuse and retaliation.

On Monday, CBS declined to take quick action against its CEO, but said it would hire outside counsel to investigate the allegations.

But the probe comes as CBS is embroiled in a high-stakes legal battle with its controlling shareholder, Shari Redstone, who CBS has accused of trying to force a merger with sister company Viacom Inc. against the wishes of Moonves and the company's independent directors. NAI, the Redstone family holding company, has denied any intention to force a merger that is not supported by both companies.

Moonves spoke on a CBS earnings call Thursday afternoon, but did not address the allegations or the Redstone dispute.

“In light of pending litigation and other pending matters, and on the advice of counsel, the scope of today's call, and any questions, will be limited to the quarterly results of the company,” said Adam Townsend, executive vice president of corporate finance, said at the beginning of the call.

Wednesday's announcement followed a meeting of the CBS board, where directors unanimously approved the selection of the two firms. The board also said it had formed a three-member special committee of directors to “facilitate the investigation.”

“Mr. Moonves will have no role in the investigation and is entirely recused from it. The board took no further action at this meeting pending discussion with counsel as to appropriate next steps,” the statement said.

The special committee includes Linda Griego, Robert N. Klieger and Bruce S. Gordon, who is also taking over as the lead independent director on the board.

CBS said that neither the board nor the company expected to comment further at this time.