Prime Minister Malcolm Turnbull has confirmed a Department of Defence leader will depart in May.
Dennis Richardson has resigned from his position as secretary of the Department of Defence, effective from 12 May.
The former diplomat has held the position since 18 October 2012.
Richardson has held various roles as a public servant including principal adviser, head of the review of the intelligence community, deputy secretary at the Department of Immigration and Ethnic Affairs, director-general of security of the Australian Security Intelligence Organisation, Australian ambassador to the United States of America and secretary of the Department of Foreign Affairs and Trade,
Richardson was appointed as an Officer of the Order of Australia (AO) for service to the community in a range of public policy areas including foreign policy, immigration and security.