11 CFR 111.17: The probable cause to believe finding; notification (52 U.S.C. 30109(a)(4)).

(a) If the Commission, after having found reason to believe and after following the procedures set forth in 11 CFR 111.16, determines by an affirmative vote of four (4) of its members that there is probable cause to believe that a respondent has violated a statute or regulation over which the Commission has jurisdiction, the Commission shall authorize the General Counsel to so notify the respondent in writing

(b) If the Commission finds no probable cause to believe or otherwise orders a termination of Commission proceedings, it shall authorize the General Counsel to so notify both respondent and complainant in writing.