Do you know of cases where the Sgt at Arms has traveled outside DC to arrest somebody for contempt or failure to appear?
I know of none.
Congress relies on the DOJ for those services.
So you contend that the authority of the Sgt at Arms is confined to DC, is that correct?
The matter of Sam Houston’s assault on William Stanbery is in the House Journal, beginning with Stanbery’s Saturday April 14 letter to the speaker of the House claiming a breach of privilege, the issuance of the arrest order that same day, the bringing of Houston before the House on Monday April 16 through to the Friday May 11 conviction and pronouncement of sentence on Monday May 14 (reprimand). All the while Houston was in the custody of the Sergeant at Arms who arrested him.
The House ordered its sergeant-at-arms to “take in custody, wherever to be found, the body of Samuel Houston”.
“Wherever to be found” is unambiguous.
U.S. House Journal. 1832. 22nd Cong., 1st sess., 14 April.
http://www.memory.loc.gov/cgi-bin/query/r?ammem/hlaw:@field%28DOCID+@lit%28hj025102%29%29: