Deputy Chancellor Richard Nyankori is leaving after four bruising years as head of special education at D.C. Public Schools. He’ll be replaced by Nathaniel Beers, director of the District’s Early Stages diagnostic center for learning disabilities. Acting Chancellor Kaya Henderson confirmed the move a few minutes ago.

Nyankori is generally credited with improving the timeliness with which families and kids can receive special ed services. But he also leaves as the District is struggling to improve its capacity to serve the more than 2,300 students who have been placed in private schools at public expense because DCPS can’t help them.

He’s the fourth major member of former chancellor Michelle A. Rhee’s senior staff to leave since Rhee quit in October. He follows chief operating officer Tony Tata, general counsel James Sandman, and data guru Erin McGoldrick out the door.