The office of the White House counsel has undergone a rapid changeover during the weeks since Kathryn Ruemmler took over as President Barack Obama’s top lawyer.

The latest hire is Leslie Kiernan, who started on Monday as a deputy counsel to the president. Kiernan was a longtime partner at Zuckerman Spaeder who focused on white-collar defense and congressional investigations, including representing Rep. Charles Rangel, D-N.Y., during most of a lengthy House ethics probe. In 2009, she did some outside work for Obama by interviewing Sonia Sotomayor prior to her Supreme Court nomination.