Top diplomatic security official leaving State Dept. while dozens of other positions remain vacant The acting chief of diplomatic security left the State Dept. on Thursday.

 -- The acting chief of diplomatic security is leaving the State Department Thursday, vacating two important roles that ensure the protection of American diplomats serving around the world.

Six months in, the Trump administration still has not named its pick for Assistant Secretary of State for Diplomatic Security -- and dozens of other top roles at the State Department -- despite then-candidate Donald Trump's constant criticism of former Secretary of State Hillary Clinton's handling of the Benghazi attack.

Bill Miller has been the Principal Deputy Assistant Secretary and Director of the Diplomatic Security Service since 2014, and he was made Acting Assistant Secretary after his predecessor Gregory Starr, a career foreign service officer, left in January.

Miller was not forced out and has not resigned in protest, according to the State Department, and with his departure, Deputy Assistant Secretary for International Programs Christian Schurman will assume the Acting Assistant Secretary role.

But the departure is causing outrage from some Democrats, who are crying hypocrisy from a president who raged about the Benghazi attack that killed four Americans serving in Libya, including Ambassador Chris Stevens.

“It's an absolute abrogation of leadership by the President and Secretary Tillerson, and it's putting American lives at risk,” said Rep. Eliot Engel, D-N.Y., ranking member of the House Foreign Affairs Committee, in a paper statement.

“If [Trump] cared about protecting our Foreign Service officers, he would have long ago nominated an Assistant Secretary for Diplomatic Security,” he added.

Miller’s departure is also a reminder of how few positions the Trump administration has filled at the State Department. They still have no senior officials confirmed by the Senate other than Secretary Rex Tillerson and his Deputy Secretary John Sullivan. Only six individuals have been named for senior positions and are awaiting confirmation.

The empty slots include four of six Under Secretary positions that are vacant; one is filled by an individual in an acting role, and the other is filled by Tom Shannon, who was confirmed by the Senate in 2016.

There are 108 other senior roles -- some that require Senate confirmation and some that don’t -- including Assistant Secretaries who are the policy lead for different regions, like the Near East or East Asia, and special envoys who are focused on particularly vexing issues or hot spots, like counterterrorism or anti-Semitism.

Of those 108 other roles, 31 are filled by someone in an acting role, and 41 are completely vacant, with two more soon to be empty: the Coordinator for Cyber Issues, in charge of diplomatic engagement on cyber issues and security, and the ambassador-at-large for Global Criminal Justice, who advises the Secretary on war crimes, crimes against humanity, and genocide.

The State Department has said that there are candidates in the pipeline who are held up by paperwork and that some roles will not be filled until Tillerson completes his review and reorganization of the agency's structure.

"All of those functions will still remain here at the State Department," State Department spokesperson Heather Nauert said Tuesday. "A different person may handle it. In some instances, it may get combined with an existing bureau. That doesn’t mean that the priority goes away and that doesn’t mean that the functions of that job or its duties will go away."

CBS News was the first to report Miller’s departure.