When the Trump supporters tell you Mueller wasn't appointed to do a criminal investigation, remind them of the law that authorized his appointment in the first place. Clearly, the law states in unambiguous terms that the special counsel is appointed for the purposes of conducting a "criminal investigation."
§ 600.1 Grounds for appointing a Special Counsel.
"The Attorney General, or in cases in which the Attorney General is recused, the Acting Attorney General, will appoint a Special Counsel when he or she determines that criminal investigation of a person or matter is warranted . . . "
https://www.law.cornell.edu/cfr/text/28/600.1
And, yes, the AG may choose to make public the Special Counsel's report.
§ 600.9 Notification and reports by the Attorney General.
"The Attorney General may determine that public release of these reports
would be in the public interest, to the extent that release would comply
with applicable legal restrictions . . ."
https://www.law.cornell.edu/cfr/text/28/600.9
