C.R.S. § 16-9-201

As used in this part 2, unless the context otherwise requires: (1) “State” includes any territory of the United States and the District of Columbia. (2) “Summons” includes a subpoena, order, or other notice requiring the appearance of a witness. (3) “Witness” includes a person whose testimony is desired in any proceeding or investigation by a grand jury or in a criminal action, prosecution, or proceeding.