A U.S. Customs and Border Protection leader who’s been deeply involved in the migrant crisis on the Southern border is getting a new job in Detroit.

Aaron Hull is chief patrol agent for the CBP’s El Paso sector. The agency confirms he’s starting as interim chief patrol agent for the Detroit sector next week.

CBP did not say why Hull is being temporarily reassigned now. Officials say in a statement that multiple members of the agency’s senior leadership are on rotating assignment.

Hull has been a chief figure in the ongoing migrant crisis at the Southern border. The El Paso sector is home to several migrant detention facilities that have been cited for inhumane conditions and treatment.

Hull has challenged those criticisms and defended his agents.