Acting Deputy Inspector General Charles K. Edwards has resigned, according to officials with the Department of Homeland Security.
Edwards has been the subject of a Senate probe of numerous allegations ranging from misusing agency money for personal travel to favoring his spouse for government positions.
Carlton Mann, the current assistant IG, will now be the acting deputy IG, DHS said.
McCaskill is chairman and Johnson is ranking minority member of the Senate's subcommittee on financial and contracting oversight. Edwards was to appear before the committee Dec. 19.
Cause of Action, a nonprofit government watchdog group, called for Edwards' removal in a July 2013 letter to President Obama, which detailed the allegations against Edwards.
Cause of Action President Dan Epstein pointed to what he called the "complete lack of transparency and accountability at DHS regarding Edwards' conduct" in a Nov. 7 statement to the Washington Examiner.