The SPLC's comments about Dees' termination hint at misconduct by Dees and potential diversity issues within the organization, although it's not clear whether the two are related in any way.
"Although he made unparalleled contributions to our work, no one's contributions can excuse that person's inappropriate conduct," read an internal email sent to SPLC staff about Dees.
"As a civil rights organization, the SPLC is committed to ensuring that the conduct of our staff reflects the mission of the organization and the values we hope to instill in the world," Cohen wrote in a statement.
"As a woman of color, the experiences of staff of color and female staff have been particularly important to me ... and we recognize that there is more work to do in the legal department and across the organization to ensure that SPLC is a place where everyone is heard and respected and where the values we are committed to pursuing externally are also being practiced externally," she wrote.
The SPLC began as a champion of racial civil rights, striking some high-profile legal blows against the Ku Klux Klan in the 1970s and 1980s.