A founder of the KIPP charter school network who was fired in 2018 after being accused of sexual misconduct is suing the organization, saying the allegations were false and that his career and reputation have been destroyed by the actions of KIPP.

KIPP executives called the lawsuit filed by Mike Feinberg “baseless and frivolous,” and said they “regret” that he is putting his accusers and the “entire KIPP community through further distress.”

KIPP has a major presence in the District, with seven campuses.

Feinberg, who in 1994 co-founded a Texas school that grew into the nation’s largest charter network, filed the lawsuit Thursday and is seeking a jury trial and punitive and other damages. He has consistently denied an allegation that he sexually abused a student in the late 1990s. The allegation triggered two investigations.

A letter issued by KIPP on Feb. 22, 2018, announcing Feinberg’s firing said an independent probe had found that an allegation of sexual abuse from two decades earlier had “credibility.” It said Feinberg denied misconduct.

The letter also cited an allegation of sexual harassment against Feinberg involving an adult employed by KIPP Houston; that case involved a financial settlement, the letter said. And it said there was another “credible” but uncorroborated allegation of sexual harassment of an adult employed by KIPP Houston. Both women were KIPP graduates.

Feinberg’s lawsuit says that he was never given “detailed information about the allegations” against him and that if he had, he could have “provided facts that would have disproved them.”

“KIPP’s public statements following Mike’s termination were false and inflammatory,” the lawsuit says. “KIPP knew that such a serious allegation would destroy Mike’s career in education and be personally devastating to him, his family and friends. But KIPP didn’t care. What mattered most to KIPP was that Mike be removed and his career be ruined. In that, KIPP succeeded.”

Sehba Ali, the chief executive of KIPP Texas, and Richard Barth, chief executive of KIPP Foundation, said in a statement: “This is a baseless and frivolous lawsuit. Mr. Feinberg’s employment was terminated last year after thorough investigations uncovered credible instances of misconduct incompatible with KIPP’s values. We regret Mr. Feinberg is choosing to put the women who came forward to share painful experiences, the witnesses who supported them, and the entire KIPP community through further distress.”

Feinberg’s firing shocked the world of charter schools, entities that are publicly funded but privately operated. He had been a leader in the charter movement, helping to pioneer the “no-excuses” model of charter schools. That model says that there are no excuses for poor academic performance by low-income students and that the achievement gap can be closed with strict behavior codes, high expectations and long school days.

One of the exhibits filed with the lawsuit is an Aug. 28, 2017, letter that Feinberg received from Ali, who was then serving as superintendent of KIPP schools in Houston. It said an investigation — conducted by KIPP’s internal counsel — found “no evidence of wrongdoing” in the nearly two-decade-old allegation of abuse of a student.

“KIPP and I consider this matter closed,” she wrote. “Mike, thank you for your professionalism and understanding while we investigated the matter.”

But the 2018 letter by KIPP said a subsequent investigation by WilmerHale, a law firm with experience investigating allegations of sexual misconduct, found information that led to Feinberg’s firing.