The acting head of U.S. Customs and Border Protection, John Sanders, has told employees he is resigning from the agency. Sanders’ announcement was emailed in a message to CBP employees, and follows allegations by independent inspectors of deplorable conditions for migrant children being held at border stations.

Sanders has served as acting commissioner since April and is the chief operating officer of the agency. Sanders previously worked as the chief technology officer for the Transportation Security Administration.

Acting head of US Customs and Border Protection tells employees he’s resigning