The Southern Poverty Law Center fired co-founder and chief litigator Morris Dees on Wednesday, the civil rights organization announced.

In a Thursday statement, SPLC President Richard Cohen stressed the importance of “ensuring that the conduct of our staff reflects the mission of the organization and the values we hope to instill in the world.”

“When one of our own fails to meet those standards, no matter his or her role in the organization, we take it seriously and must take appropriate action,” Cohen wrote. The statement did not offer specifics on the circumstances behind Dees’s termination. When pressed for more details on the decision, a spokesman for SPLC said he couldn’t “comment on the details of individual personnel” and did not anticipate any further statements on the matter.

In its story on the firing, the Montgomery Advertiser cited its 1994 investigation into the nonprofit advocacy group, in which staffers accused Dees of being a racist and alleged “discriminatory treatment of black employees.” The SPLC denied claims of racism raised in the series, the Advertiser reported.

The SPLC statement continued, “Today we announced a number of immediate, concrete next steps we’re taking, including bringing in an outside organization to conduct a comprehensive assessment of our internal climate and workplace practices, to ensure that our talented staff is working in the environment that they deserve — one in which all voices are heard and all staff members are respected."

Dees told the Associated Press his firing involved a “personnel issue,” but declined to offer more information.

“I think the Southern Poverty Law Center is a very fine group and I devoted nearly 50 years of my life to it and I’m proud of its work,” Dees told the AP. “About being fired, all I can say is it wasn’t my decision and I wish the center the best.”

Founded in the deep south on the heels of the civil rights movement, the Southern Poverty Law Center began as a small firm dedicated to fighting racism and segregation. Dees co-founded the organization in 1971 with Joseph Levin. Jr., and in the 48 years since, it has grown into a large and influential advocacy organization, cited by news outlets and lawmakers, with a revenue of more than $120,000,000, according to 2017 tax documents.

Dees’s biography was scrubbed from the SPLC’s website by Thursday afternoon, but a cached version of the page lists awards he received and lauds him for “innovative lawsuits that crippled some of America’s most notorious white supremacist hate groups.”

He famously represented the family of Michael Donald, a black 19-year-old who was brutally murdered and then hanged at the hands of the United Klans of America. The family was awarded $7 million in damages in 1987, effectively bankrupting United Klans. Donald’s mother was awarded the Klans’ only asset, their national headquarters building in Tuscaloosa.

In 2006, the National Law Journal named Dees one of the 100 most influential lawyers in the United States.

Reis Thebault contributed to this report.