SAN FRANCISCO – The staff shake-up continues at Uber, nearly a year after CEO Dara Khosrowshahi took over with a vow to remake the ride-hailing company's toxic culture.

Late Tuesday, Liane Hornsey, Uber's head of human resources, abruptly resigned after an investigation into her conduct, said the company.

The inquiry focused on how she handled employee complaints about racism, according to a Reuters report citing anonymous members of the group that brought the complaints.

Hornsey leaves just one month after the equally abrupt departure of Uber's chief brand officer, Bozoma Saint John, who now leads marketing at Los Angeles talent agency Endeavor. Saint John, who previously had worked at Apple, became the highest-ranking African-American at Uber when she was hired last year with the mission of remaking the company's bruised brand image.

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Liane Hornsey took over as Uber's chief human resources officer in January, shortly before the company became mired in a series of scandals. She is seen here speaking with Uber's new head of diversity initiatives, Bernard Coleman III.
Martin E. Klimek, Special for USA TODAY

According to Reuters, an anonymous group of Uber employees of color charged that Hornsey and Uber's human resources department ignored complaints about racist behavior at the company.

The group also maintained that Hornsey used discriminatory language and made derogatory comments about Saint John as well as the company's global head of diversity and inclusion, Bernard Coleman, who is also African-American. 

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UBER CEO Dara Khosrowshahi on October 31, 2017, for a meeting with Brazilian Finance Minister Henrique Meirelles in Brasilia, Brazil
Sergio LIMASERGIO LIMA/AFP/Getty Images

The stature of Coleman, who came to Uber after handling diversity issues for Hillary Clinton's failed presidential campaign, appeared on the brink of blooming after an investigation into Uber's culture by former U.S. attorney general Eric Holder resulted in a series of recommendations that included having Coleman report to the CEO.

But Uber did not act on that suggestion, and in January hired Bo Lee Young as its chief diversity and inclusion officer. Coleman reports to Young, who reports to the head of HR.

The aggrieved Uber employees threatened to go public with its complaints about Hornsey if Uber did not investigate. Uber's new chief legal officer, Tony West, retained Los Angeles-based law firm Gibson Dunn to look into the allegations. Gibson Dunn concluded that some of the charges were founded, Reuters said.

Uber spokesperson MoMo Zhou did not offer details about the specifics of the investigation but said the company was "confident (it) was conducted in an unbiased, thorough and credible manner, and that the conclusions of the investigation were addressed appropriately.”

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Bernard C. Coleman III is the new chief diversity officer at Uber.
Bernard Coleman

Zhou added that Hornsey would stay on temporarily in order to help transition one of her deputies, HR vice president Pranesh Anthapur, into her role. The company will then conduct a search for a new head of HR. 

Internal emails reviewed by USA TODAY include one from Hornsey to the staff acknowledging that the departure "comes a little out of the blue," while Khosrowshahi reported her move to Uber employees by praising her as “incredibly talented, creative and hard-working.”

Hornsey, who joined Uber 18 months ago from Google, was at the HR helm during a series of sexism scandals that included a scathing memo in February 2017 by former Uber engineer Susan Fowler. These and other revelations led to the departure last summer of co-founder and CEO Travis Kalanick.

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In an interview with USA TODAY in May 2017, Hornsey said Uber's main issues were not rooted in a company culture that condoned sexist behavior, which she said existed at many major companies, but rather that employees felt they weren't being appreciated for their hard work. 

“They need more love and respect from the company," Hornsey said. "That’s my sense of what’s wrong."

Since joining Uber from Expedia last August, Khosrowshahi has had to tackle fallout from a decade of aggressive corporate tactics that contributed to a meteoric rise from San Francisco black car app to a global transportation phenomenon with a valuation of $45 billion.

Over the years, Uber executives approved the creation of software aimed at deceiving city regulators, surreptitiously obtained the medical records of an Indian woman who was raped by her Uber driver, and maintained a fierce culture that Kalanick dubbed "always be hustlin'."

In contrast, Khosrowshahi recently was featured in a series of prime time television ads in which he didn't refer to specific past scandals but instead vows that the company's revamped culture will follow a simple guideline of trying to "do the right thing."

Follow USA TODAY reporter Marco della Cava on Twitter.