University of Southern California President C. L. Max Nikias stepped down Tuesday in the wake of a sex-abuse scandal involving a campus gynecologist in which school administrators faced criticism they ignored decades of complaints.

Nikias, who had been president since 2010, agreed to relinquish his role "effective immediately" but becomes president emeritus and a life trustee of the school, according to a letter to faculty, students and alumni from Board of Trustees Chair Rick J. Caruso.

Trustees hope to find his successor within four to six months, Caruso said.

Wanda M. Austin, who is a board member, was appointed interim president.

"She is a professional of impeccable integrity and character," Caruso wrote.

Austin holds a USC engineering degree and was president and CEO of her own company, The Aerospace Corp. She is a former member of the President's Council of Advisers on Science and Technology and currently is on the boards of Chevron and Amgen, according to Caruso.

Austin is "a strong advocate for science, technology, engineering, and math (STEM) disciplines as well as for minorities and women," he wrote.

Nikias, 65, agreed in May to step down at an unspecified date. He and the school faced accusations that they ignored decades of complaints against Dr. George Tyndall, a gynecologist who worked at a university clinic for 30 years.

Tyndall, who has since retired, is the focus of some two dozen lawsuits and a police investigation into allegations involving at least 50 women.

The lawsuits allege Tyndall routinely made crude comments, took inappropriate photographs and forced plaintiffs to strip naked and groped them under the guise of medical treatment.

Nikias also came under fire after reports in the Los Angeles Times that USC medical school dean Dr. Carmen Puliafito associated with criminals and people who used drugs and had been captured on video apparently smoking methamphetamine.

Puliafito gave up his post in 2016 but remained a faculty member until USC fired him last year.

In his letter, Caruso promised reforms.

"As I have said previously, it is evident that the recent crises have resulted from systemic and cultural failures," he wrote. "Both the behavior and the environment that allowed it to persist are inexcusable and will no longer be tolerated."

Caruso said a law firm hired in May to investigate the Tyndall allegations had interviewed more than 100 witnesses and collected 4.5 million documents.

He also noted that the school has a newly formed Office for Professional Ethics to monitor and investigate complaints.