Associate Deputy Attorney General Scott Schools, a senior career lawyer at the Justice Department and a key adviser to Deputy Attorney General Rod Rosenstein, will leave the DOJ, NPR reported Tuesday, citing two unnamed people familiar with Schools’ decision.

NPR described Schools as a critical “strategic counselor and repository of institutional memory and ethics at the DOJ,” advising top players at the Justice Department and helping to oversee special counsel Robert Mueller’s probe.

He was hired to his current role by former Deputy Attorney General Sally Yates in October 2016.

Two unnamed sources, respectively, told NPR that there was “no sign he was being pushed out,” and that “Schools was not leaving because of a disagreement with DOJ leadership.”

A former colleague of Schools’ at the U.S. Attorney’s Office in South Carolina told Slate last year that Schools was “the most important unknown person in D.C.,” NPR noted.

Read NPR’s full report here.