Sergeant at Arms and Doorkeeper of the United States Senate

The Sergeant at Arms of the Senate or originally known as the Doorkeeper of the Senate from the First Congress until the Eighth Congress (April 7, 1789 – March 3, 1803) is the highest ranking Federal Law Enforcement Officer in the Senate of the United States. One of the chief roles of the Sergeant at Arms is to hold the gavel used at every session. The Sergeant at Arms can also compel the attendance of an absent Senator when ordered to do so by the Senate.

With the Architect of the Capitol and the House Sergeant at Arms, he serves on the Capitol Police Board, responsible for security around the building.

The Sergeant at Arms can, upon orders of the Senate, arrest and detain any person who violates Senate rules, including the president.

The Sergeant at Arms is also the executive officer for the Senate and provides Senators with computers, equipment, and repair and security services.

In March, 2014, Senate Majority Leader Harry Reid announced that Terrance W. Gainer was planning on retiring as Senate Sergeant-at-Arms, and would be replaced by Senate Deputy Sergeant-at-Arms Andrew B. Willison. On January 6th, 2015, the Senate swore in the Sergeant-at-Arms for its current term, Frank J. Larkin.

...
Wikipedia