Jessica Guynn

USA TODAY

SAN FRANCISCO — Uber is under fire from two of its investors, diversity advocates Mitch Kapor and Freada Kapor Klein, who are blasting the company for hiring insiders to investigate its "toxic" and "destructive" corporate culture following sexism charges.

"To us, this decision is yet another example of Uber’s continued unwillingness to be open, transparent, and direct," they wrote in an open letter to Uber published on Medium.

Uber released a statement from the lawyers in charge of the investigation pledging it would be "thorough, impartial and objective."

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On Sunday Uber CEO Travis Kalanick opened an internal investigation into claims of sexual harassment made by a former engineer. Susan Fowler said she reported that she was sexually harassed by her direct supervisor but the company's human resources department did nothing. The post on her personal blog went viral.

In charge of the investigation are Liane Hornsey, the company’s new chief of human resources, and former Attorney General Eric Holder, now in private practice. Uber board member Arianna Huffington has also taken an active role.

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The Kapors say they are disappointed and frustrated that Uber has failed to change its "toxic" company culture, despite a workshop on unconscious bias lead by Freada Kapor Klein in 2015 and numerous contacts with senior officials at Uber, though "notably" not Kalanick. They said they fear that Uber will return to business as usual after the publicity dies down.

"We feel we have hit a dead end in trying to influence the company quietly from the inside," the two wrote. Kapor Capital, the venture capital arm of the Kapor Center for Social Impact, was an early investor in Uber.

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The final straw, they say: An independent investigation that they claim is anything but.

"Eric Holder has been working on behalf of Uber since at least last June, when he and his firm were hired to advocate on behalf of Uber to lawmakers concerning using fingerprints as part of background checks on drivers. Arianna Huffington has held a board seat for about a year and is deeply invested in the company weathering the PR crisis. As the company’s Chief Human Resources officer, Liane Hornsey reports to Travis’ executive team,' the Kapors wrote. "This group is not set up to come up with an accurate analysis of the culture and a tough set of recommendations."

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In response, Uber released a statement from Holder and his law partner Tammy Albarran.

“We are conducting this review with the highest degree of integrity and professionalism,” they said.