The Execution of Ashli Babbit

A gunman wearing a suit & tie, in the Speaker's Lobby, fired one lethal shot to the neck of a 14 year Air Force veteran. The woman died within seconds, on the marble floor landing of a staircase of the nation's capitol.
It was not a uniformed law enforcement officer, but rather a likely member of the Sergeant-At-Arms, which answers directly to Nancy Pelosi, the current Speaker of the House.