https://www.politico.com/news/2021/09/13/dept-of-homeland-security-chief-of-staff-abruptly-resigns-511650

Karen Olick, chief of staff to Department of Homeland Security Secretary Alejandro Mayorkas, announced on Monday that she will be leaving for a new, undisclosed opportunity.

Jennifer Higgins, the current associate director of Refugee, Asylum and International Operations at U.S. Citizenship and Immigration Services, will step in as a temporary chief of staff until a new appointment is made, according to officials in the department. Olick plans to leave DHS at the end of the month.