Rand Beers
He also served as acting Secretary of Homeland Security following the resignation of Secretary Janet Napolitano on September 6 , 2013 until Jeh Johnson assumed that office on December 23 , 2013 . 
<triplet> Janet Napolitano <subj> Secretary of Homeland Security <obj> position held <triplet> Jeh Johnson <subj> Secretary of Homeland Security <obj> position held