Tim Ballard had fashioned himself into a made-for-Hollywood hero.

For years, he led a nonprofit that proclaimed daring undercover missions to rescue children from the horrors of international sex trafficking. Politicians embraced his call for more barriers on the Southern border to block smuggling. President Donald J. Trump brought him on as an adviser. Last year, the hit movie “Sound of Freedom” showcased his life and work, making more than $250 million and becoming one of the most successful independent films of all time.

But while the world knew him as a champion of the vulnerable, many of the women he worked with now tell a much darker story: that Mr. Ballard himself was grooming, manipulating, harassing and sexually assaulting women. In lawsuits beginning last year, the women said that Mr. Ballard preyed on their desire to help trafficking victims, coercing or forcing them into sexual encounters as part of their undercover work in brothels, strip clubs and massage parlors.

A former Homeland Security agent, Mr. Ballard had built his nonprofit, Operation Underground Railroad, at a time when the issue of child sex trafficking was already on the rise. High-profile cases — some of them appallingly real, some of them inventions of conspiracy theorists — drove outrage about minors being forced into sexual servitude and exploited by U.S. elites.

Mr. Ballard won credibility across the varied worlds of religion, law enforcement, media, politics and entertainment. By 2020, Operation Underground Railroad was raising nearly $50 million a year in donations, with a roster of supporters that included the conservative media mogul Glenn Beck, the motivational speaker Tony Robbins and the Pittsburgh Steelers coach Mike Tomlin.

In Utah, where the organization’s leadership is based, Mr. Ballard talked up his close connections to the Church of Jesus Christ of Latter-day Saints, at times appearing alongside one of the church’s 12 powerful apostles.